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Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
United States Geological Survey Water-Supply Paper 2433
Prepared in cooperation with the Colorado Department of Highways, Arizona Depart ment of Transportation, California Department of Transportation, Idaho Depart ment of Transportation, Nevada Department of Transportation, New Mexico State Highway and Trans portation Department, Oregon Department of Transportation, Texas Depart ment of Transportation, and Utah Department of Transportation
science fora changing world
U.S. Department of the Interior
U.S. Geological Survey
ERRATA SHEETU.S. Geological Survey Water-Supply Paper 2433
Subsequent to publication of U.S. Geological Survey Water-Supply Paper 2433, "Methods for estimating magnitude and frequency of floods in the southwestern United States," errors were found on pages 48 and 52.
ERROR CORRECTION
Page 48- Table 11. Exponents for the elevation factor in the equations for the 2-year, 5-year, and 10-year recurrence intervals are negative values.
Page 52- Table 13. Exponents for the elevation factor in the equations for the 2-year, 5-year, 10- year, and 25-year recurrence intervals are negative values.
The exponents should be positive values.
The exponents should be positive values.
We apologize for the inconvenience these errors may have caused.
Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
By BLAKEMORE E. THOMAS, H.W. HJALMARSON, and S.D. WALTEMEYER
Prepared in cooperation with the Colorado Department of Highways, Arizona Department of Transportation, California Department of Transportation, Idaho Department of Transportation, Nevada Department of Transportation, New Mexico State Highway and Transportation Department, Oregon Department of Transportation, Texas Department of Transportation, and Utah Department of Transportation
U.S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2433
U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary
U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director
Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
UNITED STATES GOVERNMENT PRINTING OFFICE: 1997
For sale by theU.S. Geological SurveyBranch of Information ServicesBox 25286Federal CenterDenver, CO 80225
Library of Congress Cataloging in Pubiication Data
Thomas, Blakemore E.Methods for estimating magnitude and frequency of floods in the south
western United States / by Blakemore E. Thomas, H.W. Hjalmarson, and S.D. Waltemeyer; prepared in cooperation with the Colorado Department of Highways ... [et al.].
p. cm. (U.S. Geological Survey Water-Supply Paper 2433)Originally published: Tucson, Ariz. : U.S. Geological Survey, 1994, in
series: U.S. Geological Survey Open-File Report 93-419Includes bibliographical references.Supt. of Docs, no.: 119.13:24331. Flood forecasting Southwestern States. I. Hjalmarson, H.W. II.
Waltemeyer, Scott D. III. Colorado. Dept. of Highways. IV. Title. V. Series GB1399.4.S685T482 1995551.48'9'0979 dc20 95-12385
CIP ISBN 0-607-87035-4
CONTENTS
Abstract................................................................................................................................................................. 1Introduction...................................................................................................................................................................... 2
Purpose and Scope.................................................................................................................................................2Previous Investigations .........................................................................................................................................4
Description of Study Area..............................................................................................................................................4Physiography and Drainage ..................................................................................................................................4Climate ...................................................................................................................................................................6Flood Hydrology ....................................................................................................................................................7
Meteorologic and Hydrologic Characteristics ........................................................................................... 7Basin and Channel Characteristics ............................................................................................................. 8
Description of Methods ................................................................................................................................................ 13Gaged Sites .......................................................................................................................................................... 13Sites Near Gaged Sites on the Same Stream .................................................................................................... 14Ungaged Sites ...................................................................................................................................................... 14
Models......................................................................................................................................................... 15Explanatory Variables ............................................................................................................................... 15Flood Regions and Regression Equations................................................................................................ 16Transition Zones ........................................................................................................................................ 19
Excluded Streams and Distributary-Flow Areas............................................................................................... 20Alternative Methods ............................................................................................................................................20Assumptions and Limitations of Methods......................................................................................................... 21
Flood-Frequency Relations at Gaged Sites..............................................................................................21Regional Flood-Frequency Relations .......................................................................................................21
Application of Methods ................................................................................................................................................34Sites Near Gaged Sites on the Same Stream ....................................................................................................35Ungaged Sites ......................................................................................................................................................35
Site with a Drainage Area in One Flood Region ....................................................................................37Site with a Drainage Area in Two Low- to Middle-Elevation Flood Regions ....................................39Low- to Middle-Elevation Site Near the High-Elevation Flood Region ..............................................41
Analysis of Gaging-Station Records ...........................................................................................................................46Records Used .......................................................................................................................................................47Stationarity and Trend Tests...............................................................................................................................49Flood-Frequency Analyses .................................................................................................................................51
Low Outliers and Low-Discharge Threshold ..........................................................................................55High Outliers and Historical Periods .......................................................................................................59Sharp Breaks or Discontinuities in Plotted Peaks...................................................................................61Gaged Sites with Inadequate Samples or Non-Log-Pearson Type III Distribution .............................64Mixed Populations .....................................................................................................................................67Regional Skew Coefficient .......................................................................................................................74Summary of Analyses................................................................................................................................86
Regional Analysis .........................................................................................................................................................87Multiple Regression ............................................................................................................................................87
Models Investigated ...................................................................................................................................87Explanatory Variables Investigated.......................................................................................................... 88Results......................................................................................................................................................... 89
Hybrid Method.....................................................................................................................................................95Transition Zones................................................................................................................................................ 100
Additional Data and Study Needs ............................................................................................................................. 101Summary............................................................................................................................................................ 102References Cited .........................................................................................................................................................104Basin, Climatic, and Flood Characteristics for Streamflow-Gaging Stations in the Southwestern United States ..... 109
Contents
FIGURES
1 2. Maps showing:1. Area of study................................................................................................................................... 32. Physiographic provinces in the study area....................................................................................... 6
3 5. Graphs showing:3. Relation between latitude and the maximum unit-peak discharge of record at gaged
sites in the southwestern United States................................................................................... 94. Relation between site elevation, latitude, and maximum unit-peak discharge of record
at gaged sites in the southwestern United States.............................................................................. 115. Estimated elevation threshold for large floods caused by thunderstorms
in the southwestern United States.................................................................................................... 126 16. Maps showing flood regions in:
6. Study area........................................................................................................................................ 227. Arizona............................................................................................................................................ 238. California................................................................................... ..................................................... 249. Colorado.......................................................................................................................................... 26
10. Idaho................................................................................................................................................ 2711. New Mexico..................................................................................................................................... 2812. Nevada............................................................................................................................................. 2913. Oregon............................................................................................................................................. 3014. Texas................................................................................................................................................ 3115. Utah................................................................................................................................................. 3216. Wyoming......................................................................................................................................... 33
17 49. Graphs showing:17. Relation between maximum peak discharge of record and drainage area for gaged
sites in the study area...................................................................................................................... 3418. Joint distribution of mean annual precipitation and drainage area for gaged sites
in the High-Elevation Region 1....................................................................................................... 3619. Relations between 100-year peak discharge and drainage area and plot of maximum
peak discharge of record and drainage area for gaged sites in the High-Elevation Region 1.......................................................................................................................................... 37
20. Joint distribution of mean basin elevation and drainage area for gaged sites in theNorthwest Region 2......................................................................................................................... 38
21. Relations between 100-year peak discharge and drainage area and plot of maximumpeak discharge of record and drainage area for gaged sites in the Northwest Region 2................. 39
22. Joint distribution of mean annual precipitation and drainage area for gaged sites inthe South-Central Idaho Region 3................................................................................................... 40
23. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the South-Central Idaho Region 3.......................................................................................................................................... 41
24. Joint distribution of mean basin elevation and drainage area for gaged sites in theNortheast Region 4.......................................................................................................................... 42
25. Relations between 100-year peak discharge and drainage area and plot of maximumpeak discharge of record and drainage area for gaged sites in the Northeast Region 4.................. 43
26. Joint distribution of latitude and drainage area for gaged sites in the Eastern SierrasRegion 5.......................................................................................................................................... 44
27. Joint distribution of mean basin elevation and drainage area for gaged sites in theEastern Sierras Region 5................................................................................................................. 44
28. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Eastern Sierras Region 5.......................................................................................................................................... 45
29. Joint distribution of mean basin elevation and drainage area for gaged sites in theNorthern Great Basin Region 6....................................................................................................... 46
30. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northern Great Basin Region 6................................................................................................................................ 47
IV Contents
31. Joint distribution of mean basin elevation and drainage area for gaged sites inthe South-Central Utah Region 7...................................................................................... 48
32. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the South-Central Utah Region 7......................................................................................................................................... 49
33. Joint distribution of mean basin elevation and drainage area for gaged sites in theFour Corners Region 8................................................................................................................... 50
34. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Four Corners Region 8....................................................................................................................................... 51
35. Joint distribution of mean basin elevation and drainage area for gaged sites in theWestern Colorado Region 9........................................................................................................... 52
36. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Western Colorado Region 9......................................................................................................................................... 53
37. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southern Great Basin Region 10....................................................................................................................................... 54
38. Joint distribution of mean annual evaporation and drainage area for gaged sites in theNortheastern Arizona Region 11.................................................................................................... 56
39. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northeastern Arizona Region 11......................................................................................................................... 57
40. Joint distribution of mean basin elevation and drainage area for gaged sites in theCentral Arizona Region 12............................................................................................................ 58
41. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Central Arizona Region 12....................................................................................................................................... 59
42. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southern Arizona Region 13....................................................................................................................................... 60
43. Joint distribution of mean basin elevation and drainage area for gaged sites in theUpper Gila Basin Region 14.......................................................................................................... 62
44. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Upper Gila Basin Region 14....................................................................................................................................... 63
45. Joint distribution of longitude and drainage area for gaged sites in the Upper RioGrande Basin Region 15................................................................................................................ 64
46. Joint distribution of mean basin elevation and drainage area for gaged sites in theUpper Rio Grande Basin Region 15............................................................................................... 64
47. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Upper Rio Grande Basin Region 15............................................................................................................................. 65
48. Joint distribution of mean annual evaporation and drainage area for gaged sites in theSoutheast Region 16....................................................................................................................... 66
49. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southeast Region 16....................................................................................................................................... 67
50 51. Maps showing:50. Gaging stations used in this study.................................................................................................. 6851. Gaging stations with an applied low-discharge threshold.............................................................. 71
52 53. Graphs showing:52. Flood-frequency relations for Santa Cruz River near Lochiel, Arizona (09480000)...................... 7253. Flood-frequency relations for New River near Glendale, Arizona
(09513910)..................................................................................................................................... 73
Contents V
54. Map showing gaging stations with a high outlier........................................................................... 7455. Graph showing examples of gaging-station records with sharp breaks or discontinuities
in their plotted peaks....................................................................................................................... 7556. Map showing gaging stations with sharp breaks or discontinuities in their plotted peaks.............. 7657. Graph showing examples of plotted peaks for gaging stations with samples that are
inadequate to define a flood-frequency relation.............................................................................. 7758. Map showing gaging stations with samples that are inadequate to define a flood-
frequency relation........................................................................................................................... 7859. Graph showing elevation zone for mixed population of floods caused by thunderstorms
and snowmelt in the southwestern United States............................................................................ 8060. Map showing gaging stations with an analysis for a mixed population of floods caused
by thunderstorms and snowmelt...................................................................................................... 8261-63. Graphs showing flood-frequency relations for:
61. South Fork of Rock Creek near Hanna, Utah (09278000).............................................................. 8362. Big Creek near Randolph, Utah (10023000)................................................................................... 8463. Mill Creek near Moab, Utah (09184000)........................................................................................ 85
64-66. Graphs showing relation between:64. 100-year peak discharge and drainage area for Southern Arizona Region 13................................. 9365. Logarithm of 100-year peak discharge and drainage area for Southern Arizona
Region 13........................................................................................................................................ 9466. 100-year peak discharge and drainage area for the northern, middle, and southern
parts of the study area..................................................................................................................... 98
TABLES
1. Areas of study of previous regional flood-frequency investigations...................................................... 52. Relation between season of occurrence of annual peak discharges and latitude in the
southwestern United States.................................................................................................................... 83. Magnitude of maximum unit-peak discharge of record compared with latitude and
proportions of peaks caused by thunderstorms in the southwestern United States................................. 104. Summary of selected characteristics of flood regions in the southwestern United States...................... 18
5-9. Generalized least-squares regression equations for estimating regional flood-frequency relations for the:
5. High-Elevation Region 1................................................................................................................ 366. Northwest Region 2........................................................................................................................ 387. South-Central Idaho Region 3......................................................................................................... 408. Northeast Region 4......................................................................................................................... 429. Eastern Sierras Region 5................................................................................................................. 45
10. Hybrid equations for estimating regional flood-frequency relations for the NorthernGreat Basin Region 6............................................................................................................................. 46
11-13. Generalized least-squares regression equations for estimating regional flood-frequency relations for the:11. South-Central Utah Region 7.......................................................................................................... 4812. Four Corners Region 8.................................................................................................................... 5013. Western Colorado Region 9............................................................................................................ 52
14. Hybrid equations for estimating regional flood-frequency relations for the Southern...........................Great Basin Region 10........................................................................................................................... 54
15. Hybrid equations for estimating regional flood-frequency relations for the Northeastern.....................Arizona Region 11................................................................................................................................. 56
16-19. Generalized least-squares regression equations for estimating regional flood-frequency relations for the:16. Central Arizona Region 12............................................................................................................. 5817. Southern Arizona Region 13........................................................................................................... 6018. Upper Gila Basin Region 14........................................................................................................... 6219. Upper Rio Grande Basin Region 15............................................................................................... 65
VI Contents
20. Hybrid equations for estimating regional flood-frequency relations for the SoutheastRegion 16............................................................................................................................................... 66
21. Drainage area and years of systematic record at gaging stations in the southwesternUnited States.......................................................................................................................................... 69
22. Significance of trends over time in annual peak discharges for gaging stations withat least 30 years of record in the southwestern United States................................................................ 69
23. Summary of characteristics of station flood-frequency relations in the southwesternUnited States.......................................................................................................................................... 69
24. Characteristics of station flood-frequency relations compared with basin and climaticcharacteristics in the southwestern United States................................................................................... 70
25. Percentage of gaging stations with undefined flood-frequency relations compared withbasin and climatic characteristics in the southwestern United States..................................................... 79
26. Summary of analyses of mixed-population flood records for the southwestern UnitedStates...................................................................................................................................................... 81
27. Correlation matrix with 100-year peak discharge and explanatory variables for thesouthwestern United States.................................................................................................................... 96
28. Stepwise ordinary least-squares regression of 7-year discharge and basin and climaticcharacteristics for the entire low- to middle-elevation study area.......................................................... 97
29. Summary of estimated prediction errors of generalized least-squares regional models......................... 10030. Summary of residuals from low- to middle-elevation regional models, the high-elevation
model, and a composite model for gaged sites in a transition zone....................................................... 104
CONVERSION FACTORS AND VERTICAL DATUM
Multiply
inch (in.) foot (ft)
square mile (mi2) cubic foot per second (ft3/s)
cubic foot per second per square mile [(ft3/s)/mi2]
By
25.40 0.3048 2.590 0.02832 0.01093
To obtain
millimeter meter square kilometer cubic meter per second cubic meter per second per square kilometer
Air temperatures are given in degrees Fahrenheit (°F), which can be converted to degrees Celsius (°C) by the following equation:°C=5/9(°F)-32
Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.
Contanta VII
Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United StatesBy Blakemore E. Thomas, H.W. Hjalmarson, and S.D. Waltemeyer
Abstract
Equations for estimating 2-, 5-, 10-, 25-, 50-, and 100-year peak discharges at ungaged sites in the southwestern United States were developed using generalized least-squares multiple-regression techniques and a hybrid method that was developed in this study. The equations are applicable to unregulated streams that drain basins of less than about 200 square miles. Drainage area, mean basin elevation, mean annual precipitation, mean annual evaporation, latitude, and longitude are the basin and climatic characteristics used in the equations. The study area was divided into 16 flood regions; Region 1 is a high-elevation region that in cludes the entire study area.
Floods in the northern latitudes of the study area generally are much smaller than floods in the southern latitudes. Typical unit peak discharges of record range from 316 cubic feet per sec ond per square mile for sites between 29° and 37° latitude to 26 cubic feet per second per square mile for sites between 41° and 45° latitude. An elevation threshold exists in the study area above which large floods caused by thun derstorms are unlikely to occur. For sites between 29° and 41° latitude, the elevation threshold is approximately
7,500 feet. For sites between 41° and 45° latitude, the elevation threshold decreases in a northward direction at a rate of about 300 feet for each degree of latitude.
Detailed flood-frequency analyses were made of more than 1,300 gaging stations with a combined 40,000 sta tion years of annual peak discharges through water year 1986. The log-Pearson Type III distribution and the method of moments were used to define flood-frequency rela tions. A low-discharge threshold was applied to about one-half of the sites to adjust the relations for low outliers. With few exceptions, the use of the low-discharge threshold resulted in markedly better- appearing fits between the computed relations and the plotted annual peak dis charges. After all adjustments were made, 80 percent of the gaging stations were judged to have adequate fits of the com puted relations to the plotted data. The individual flood- frequency relations were judged to be unreliable for the remaining 20 percent of the stations because of extremely poor fits of the computed rela tions to the data, and these relations were not used in the generalized least-squares regional-regression analysis. Most of the stations with unre
liable relations were from extremely arid areas with 43 percent of the stations having no flow for more than 25 per cent of the years of record. A new regional flood-frequency method, which is named the hybrid method, was developed for those more arid regions.
An analysis of regional skew coefficient was made for the study area. The methods of attempting to define the varia tion in skew by geographic areas or by regression with basin and climatic characteris tics all failed to improve on a mean of zero for the sample. The regional skew used in the study, therefore, was the mean of zero with an associated error equal to the sample variance of 0.31 log units.
Generalized least-squares regression was used to define the regression models in 12 regions where sufficient data allowed a reasonable regional model to be developed using the flood-frequency relations at gaged sites. Four regions had more than 30 percent of the gaged sites with no defined relations; thus, the regression method was not used because of the large amount of missing information. The hybrid method was used in those four regions because individual fitted flood- frequency relations are not required and data from all gag ing stations in a region can be
Abstract
used. Average standard error of prediction of the generalized least-squares regional models for 12 regions ranged from 39 to 95 percent for the 100-year peak discharge, and only three of those models have errors of greater than 70 per cent. The estimated average standard error of the hybrid models for four regions, which was computed differently than generalized least- squares errors, ranged from 0.44 to 1.8 log units for the 100-year peak discharge.
INTRODUCTION
Flood-frequency information is needed for the cost-effective design of bridges, culverts, dams, and embankments and for the management of flood plains. In this study, methods were developed by the U.S. Geological Survey for estimating magni tude and frequency of floods of streams in basins of less than about 200 mi2 in the arid southwestern United States. The reliable estimation of flood- frequency relations for both gaged and ungaged streams that drain these arid basins is complex because rainfall is variable in time and space and the physiography of the drainage basins is extremely variable. The development of accu rate flood-frequency relations at gaged sites is unlikely in some areas because of the variability of annual peak discharges and short records. At some sites, most years have no flow. At other sites, commonly used probability distributions do not
appear to fit the plot of annual peak discharges.The understanding of the flood characteristics
of streams in arid lands is improved because of the regional perspective of this study. A large data base of streamflow-gaging-station records was evaluated for most of the southwestern United States. The study was done in cooperation with the Departments of Transportation of nine States Colorado, Arizona, California, Idaho, Nevada, New Mexico, Oregon, Texas, and Utah.
Purpose and Scope
This report describes the results of a study to develop reliable methods for estimating magnitude and frequency of floods for gaged and ungaged
streams in the southwestern United States and to improve the understanding of flood hydrology in the southwestern United States. The large study area, which encompasses most of the arid lands of the southwestern United States, provided an opportunity to examine truly regional relations. Cur rent and new methods for estimating regional flood-frequency relations and associated errors were investigated. The study area includes all of Arizona and Utah, and parts of California, Colorado, Idaho, Nevada, New Mexico, Oregon, Texas, and Wyo ming (fig. 1).
The data examined in the study include sites with drainage areas of less than 2,000 mi2 and mean annual precipitation of less than 68 in. The focus of the study, however, was on drainage areas of less than about 200 mi2 and arid areas with less than 20 in. of mean annual precipitation. The series of annual peak discharges for sites used in this study are unaffected by regulation, and the individual sites have at least 10 years of record through water year 1986.
The basic regional method used in this study is an information-transfer method in which flood- frequency relations determined at gaged sites are transferred to ungaged sites using multiple- regression techniques. Flood-frequency relations were determined at gaged sites using guidelines recommended by the Interagency Advisory Commit tee on Water Data (1982). Ordinary and generalized least-squares multiple-regression analyses were used to relate the gaged-site flood-frequency rela tions to basin and climatic characteristics.
During this study, a new method of estimating regional flood-frequency relations was developed (Hjalmarson and Thomas, 1992). The new method, named the hybrid method, combines elements of the station-year method and multiple-regression analy sis. Individual flood-frequency relations are not used in the new method; thus, the method is useful for extremely arid areas where development of reliable flood-frequency relations at gaged sites is difficult.
This regional study offers several advantages compared with previous Statewide regional studies. The large data base of more than 1,300 gaged sites with about 40,000 station years of annual maximum peaks can decrease the time-sampling error of flood estimates, which can be a problem with small data sets in the southwestern United States. Some of the recent regional studies developed for single States
Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
have large differences in the estimated flood- frequency relations at State boundaries. These different estimates of flood magnitudes at State boundaries were removed in this study. Regional relations that were derived from the large data base with a large range of values are potentially more reliable than relations derived from smaller data bases and can be used with less extrapolation for ungaged streams. The data base for this study is in
a section entitled "Basin, Climatic, and Flood Char acteristics for Streamflow-Gaging Stations in the southwestern United States" at the end of this report and hereafter is referred to as the data section.
A goal of this study was to define regional flood-frequency relations with a standard error of prediction of less than approximately 50 percent. This goal was accomplished for some regions of the study area. For the more arid regions in particular,
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Figure 1. Area of study (shaded).
Introduction
this goal was impossible to accomplish and errors in excess of 100 percent could not be reduced.
The first sections of this report serve as a design guide for engineers and hydrologists inter ested in estimating the magnitude and frequency of floods. Maps of the States are used to show flood regions because most users of the method are State oriented. These design guide sections include the design methods, the accuracy of the estimated regional relations, examples of the design methods, and maps and (or) discussions of nonapplication areas within the study area.
Previous Investigations
Many investigations have been done on regional flood-frequency relations in the study area (table 1). Five regional studies of river basins were done using the index-flood method. Benson (1964) was one of the first investigators to use the multiple-regression method.
The multiple-regression method with basin and climatic characteristics as explanatory variables has been used to develop regional flood-frequency rela tions in the 10 individual States in the study area. Studies for six individual States have used meas urements of channel geometry as a predictor of regional flood-frequency relations. An additional channel-geometry study of the western United States included the entire study area (Hedman and Osterkamp, 1982). During the past decade, studies were done using paleoflood hydrologic techniques to extend streamflow records for hundreds or thou sands of years (Kochel, 1980; Baker, 1984; Ely and Baker, 1985; Baker and others, 1987; O'Connor and others, 1986a, b; Fuller, 1987; Partridge and Baker, 1987; Roberts, 1987; Webb and others, 1988).
DESCRIPTION OF STUDY AREA
The study area is about 600,000 mi2 and includes all or parts of ten States Arizona, Califor nia, Colorado, Idaho, Nevada, New Mexico, Oregon, Texas, Utah, and Wyoming. The area is bounded by the Rocky Mountains on the east, the northern slopes of the Snake River basin on the north, the Sierra-Cascade Mountains on the west, and the international border with Mexico on the south (figs. 1, 2).
Physiography and Drainage
The topography varies between high rugged mountains and flat continuous plains. The elevation of the crestline of the Sierra-Cascade Mountains to the west and the Rocky Mountains to the east is commonly more than 10,000 ft; some peaks are more than 12,000 ft. In the interior part of the area, isolated mountains are separated by arid desert plains. Most of the mountain ranges trend north and northwest and commonly rise a few thousand feet above the adjacent alluvial plains. A large pla teau was incised by the Colorado and Green Rivers in southeastern Utah, northeastern Arizona, south western Colorado, and northwestern New Mexico.
Fenneman (1931) provided a detailed descrip tion of the physiographic provinces in the study area (fig. 2). The Northern, Middle, and Southern Rocky Mountains in the northern and eastern parts of the study area are high complex mountainous areas separated by lower basins or valleys. The Wyoming Basin province in southwestern Wyoming and northwestern Colorado lies between the South ern and Middle provinces of the Rocky Mountains. The major landform of the Wyoming Basin is an elevated plain or plateau with some isolated low mountains scattered throughout the basin.
The Colorado Plateaus province in the central part of the study area has nearly horizontal sedi mentary rocks, generally high elevations of 5,000 to 11,000 ft, and many canyons and escarpments. Landforms include plains, plateaus, pediments, and isolated mountains.
The Basin and Range province in the western and southern part of the study area has mostly iso lated block mountains separated by aggraded desert plains. The mountains commonly rise abruptly from the valley floors and have piedmont plains that ex tend downward to neighboring basin floors. Several large flat desert areas are interspersed between the mountains, and some are old lake bottoms that have not been covered with water for hundreds of years. Many of the piedmont plains contain distributary- flow areas that are composed of material deposited by mountain-front runoff.
The Sierra-Cascade Mountains province, which forms the western boundary of the study area, con sists of volcanic mountains in Oregon and northern California and a block mountain range in eastern California. The Columbia Plateaus province in the
Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Stetes
Table 1. Areas of study of previous regional flood-frequency investigations
Multiple-regression methodState Index-flood method
Basin and climate Channel geometry
Arizona
California
Colorado
Idaho
Nevada
New Mexico
Oregon
Texas
Utah
Wyoming
Multiple States
Patterson and Somers (1966)
Butler and others (1966) Patterson and Somers (1966)
Patterson and Somers (1966)
Thomas and others (1963)
Butler and others (1966) Patterson and Somers (1966)
Patterson (1965) Patterson and Somers (1966)
Thomas and others (1963) Hulsing and Kallio (1964) Butler and others (1966)
Patterson (1965)
Patterson and Somers(1966)Butler and others (1966)
Patterson and Somers(1966)Butler and others (1966)
Roeske (1978)Boughton and Renard (1984)Eychaner(1984)
No data
Wannanen and Crippen (1977) No data
McCain and Jarrett (1976) Kircher and others (1985)
Thomas and others (1973) Riggs and Harenburg (1976) Kjelstrom and Moffatt (1981)
Moore (1976)
Scott (1971)Thomas and Gold (1982) Hejl(1984) Waltemeyer (1986)
Harris and Hubbard (1982)
Massey and Schroeder (1977) Schroeder and Massey (1977)
Butler and Cruff (1971) Eychaner (1976) Thomas and Lindskov (1983) Christenson and others (1985)
Lowham (1976) Craig and Rankl (1978) Lowham (1988)
Benson(1964)
Hedman and others (1972)
Riggs and Harenburg (1976) Harenburg (1980)
Moore (1974)
Scott and Kunkler (1976)
No data
No data
Fields (1975)
Lowham (1988)
Hedman and Osterkamp (1982)
northwestern part of the study area mainly has nearly horizontal sheets of lava with a flat or rolling surface and some broad alluvial terraces and valleys interspersed throughout the area.
Major drainage basins in the study area include the entire Colorado River basin, the upper Rio Grande basin, interior drainage of streams in the Great Basin, and part of the Snake River basin (fig. 1). The large rivers originate in high- elevation mountainous areas where precipitation is
abundant and pass through arid desert areas on their way to the oceans or play as.
Most of the streams in the study area flow only in direct response to rainfall or snowmelt. In the northern latitudes and at the higher elevations where the climate is cooler and more humid, most of the streams flow continuously. Streams in allu vial valleys and base-level plains are perennial or intermittent where the stream receives ground-water outflow. Small streams in the southern latitudes
Description of Study Area
commonly flow only a few hours during a year (Hjalmarson, 1991).
Climate
An arid or semiarid climate in the middle lati tudes exists where potential evaporation from the soil surface and from vegetation exceeds the aver age annual precipitation (Trewartha, 1954, p. 267). About 90 percent of the study area is arid or semi-
49° / 120
arid and has a mean annual precipitation of less than 20 in. In addition to the generally meager precipitation, the climate of the study area is characterized by extreme variations in precipitation and temperature. Mean annual precipitation ranges from more than 50 in. in the Sierra-Cascade Moun tains in California to less than 3 in. in the deserts of southwestern Arizona and southeastern California. Temperatures range from about 110°F in the south western deserts in the summer to below 0°F in the northern latitudes and mountains in the winter. Pre-
100°
45
LOWER CALIFORNIAN^i
PROVINCE 33°\
100 MILES_I
0 100 KILOMETERS
29°
GULF OF MEXICO
Modified from Fenneman (1931)
Figure 2. Physiographic provinces in the study area.
Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
cipitation in the study area is variable temporally and spatially. As a general rule, the relative variabil ity of annual precipitation increases with decreasing annual amounts (Trewartha, 1954, p. 269). In some extremely arid parts of the study area, the mean annual precipitation has been exceeded by the rainfall from one or two summer thunderstorms.
Climate in the study area generally is influenced by latitude, elevation, and orographic effects. In the desert lowlands of the southern part of the study area, the climate is hot and dry. The high valleys of the north are cooler and also dry. Elevation has a complex effect on climate. On a small scale, annual precipitation increases and mean temperature de creases with increased elevation. Thus, throughout the study area, the climate can range from humid to arid within a few miles between mountains and adjacent valleys. On a larger scale, large elevation differences that are consistent over large areas cause an orographic effect on the climate. Areas on the leeward side of major mountain ranges such as the Sierra-Cascade Mountains of Oregon and Cali fornia receive small quantities of precipitation. Areas on the windward side of land masses that intercept prevailing wind movement, such as the southern edge of the Colorado Plateaus in central Arizona, receive large quantities of precipitation.
Flood Hydrology
Floods have been assigned many definitions on the basis of quantity and expected frequency of streamflow, relation of flow to the geometry of the stream channel, and possible damage to property. Thus, a flood can be any flow event that is large, that overtops the natural or artificial banks of a stream, or that results in loss of life or damage to property.
Meteorologic and Hydrologic Characteristics
Floods in the study area can be generated by several processes. High rates of rainfall that exceed infiltration capacity of the soils can cause rapid run off and floods. Rapid melting of a snowpack as a result of high temperatures or rainfall on a snow- pack also can cause floods. A unique combination of accumulation of snowpack, melting of the snow- pack, freezing of the melted snow and ground, and
then rainfall has caused large floods in northern Nevada and southern Idaho. Nearly all streams in the study area have a mixed population of floods. A mixed population is defined as an aggregation of floods that are caused by two or more distinct and generally independent hydrometeorologic condi tions, such as snowmelt and rainfall. Populations of floods in the study area are those caused by snow- melt; by rainfall from thunderstorms, midlatitude cyclonic storms, upper-level low-pressure systems, and tropical cyclones; and by rainfall on snow. The distribution of the populations of floods is related to distance from moisture sources and elevation.
Much of the moisture in the study area comes from the Pacific Ocean and the Gulfs of California and Mexico (fig. 1). In the northern part of the study area, moisture comes from all three sources, and midlatitude cyclonic storms and upper-level low-pressure systems that move from west to east during October through May are the most frequent weather systems. Rainfall or snow and subsequent snowmelt from these weather systems cause most of the larger floods. In the southern part of the study area, the Gulf of Mexico and Gulf of California are the primary moisture sources, and rainfall from summer thunderstorms causes most of the larger floods. Elevation also influences the type of precipi tation; snow commonly falls in the high elevations, and rain commonly falls in low elevations. Snow can occur in most of the study area; however, most of the accumulation of snow is at high elevations and in the northern latitudes. Because of a cooler climate, more floods from snowmelt occur at lower elevations in the northern latitudes than in the southern latitudes.
A general picture of the areal distribution of populations of floods in the study area can be seen by examining the season of occurrence of annual peak discharges. Each population of floods usually occurs during a particular season; therefore, the populations can be placed into three groups peaks that occur in the spring, summer, or fall and winter. Snowmelt causes floods in the spring, and thunder storms cause floods in the summer. Midlatitude cyclonic storms, upper-level low-pressure systems, and tropical cyclones result in fall or winter floods.
The season of occurrence of annual peak dis charges in the study area primarily is related to latitude (table 2). For sites between 29° and 37° latitude, the average gaging-station record has 14 percent of its peaks in the spring, 60 percent in the
Description of Study Area
Table 2. Relation between season of occurrence of annual peak discharges and latitude in the southwestern United States
Average percentage of peak discharges in gaging-station records
Latitude, in degrees
29-37
37-39
39-41
41-45
Spring
April- June
14
49
62
70
Summer
July- September
60
38
22
6
Fall-winter
October- March
26
13
16
24
summer, and 26 percent in the fall and winter. Thus, most of the annual peaks in the southern part of the study area are caused by summer thunder storms. At an average site between 41° and 45° latitude, only 6 percent of the annual peaks occur in the summer. Spring peaks (snowmelt) have the opposite relation to latitude; the percentage increases from 14 percent in the south to 70 percent in the north. The percentage of fall-winter peaks (rainfall from cyclonic storms, upper-level lows, and tropical cyclones) is about 25 percent in the south and north, and only 13 to 16 percent in the middle part of the study area. The lower percentage of winter peaks in the middle part of the area may be related to the cold winters in the midlatitudes and to the orographic effect of the high elevations of the Sierra-Cascade Mountains between 35° and 41° latitude, which acts as a barrier to the fall- winter systems.
Summer thunderstorms generally result in the largest unit-peak discharges in the study area. To examine the magnitude and distribution of thunder storm-caused peaks, the maximum peak discharge of record for all gaged sites was divided by its drainage area, and that value, called unit-peak dis charge, was compared with site characteristics. All unit-peak discharges greater than 100 (ft3/s)/mi2 were caused by rainfall except for one site in Idaho that had a discharge of 130 (ft3/s)/mi2 caused by snowmelt. Summer thunderstorms caused about 90 percent of the maximum unit peaks greater than 100 (ft3/s)/mi2 . The remainder of the maximum unit peaks greater than 100 (ft3/s)/mi2 were caused by rainfall from other types of storms.
The magnitude of the unit peaks decreases in a northward direction with a significant decrease at 41° latitude (fig. 3). In the southern part of the
study area (between 29° and 37° latitude), where 63 percent of the maximum peaks were caused by summer thunderstorms, the average maximum unit- peak discharge of record is 316 (ft3/s)/mi2 (table 3). In the northern part of the study area (between 41° and 45° latitude), the average maximum unit-peak discharge of record is 26 (ft3/s)/mi2 , and only 9 percent of those peaks were caused by summer thunderstorms. Typical peak discharges for major floods in the southern latitudes are nearly 10 times greater than peak discharges for major floods in the northern latitudes.
Jarrett (1987) and Tunnell (1991) determined that large floods caused by thunderstorms are unlikely to occur above an elevation threshold. The physical basis of this threshold probably is related to factors that include available energy and mois ture in the atmosphere for the convective process and a generally abundant cover of vegetation in high elevations below the timber line that enhances infiltration of rainfall and thereby reduces runoff.
The elevation threshold of large floods that result from thunderstorms was investigated for this study by comparing the relation between the maxi mum unit-peak discharge of record and site elevation. The relations discovered in this study agree with relations presented by Jarrett (1987). For sites between 29° and 41° latitude, the elevation threshold for large floods caused by thunderstorms is about 7,500 ft (fig. 4). For sites between 41° and 45° latitude, the estimated elevation threshold decreases in a northward direction at a rate of about 300 ft for each degree of latitude (fig. 5), and the general magnitude of unit peaks is much smaller than for sites south of 41° latitude (fig. 4).
Basin and Channel Characteristics
When runoff from rainfall or snowmelt begins, drainage-basin and stream-channel characteristics affect the quantity and rate of runoff. Drainage- basin and stream-channel characteristics that influence flood runoff are vegetation, topography and orographic influences, topography and stream channels, and distributary-flow areas.
Vegetation. Most of the study area is sparsely covered with vegetation because of the arid climate. A dense cover of vegetation exists only in the high elevations of the mountains where precipitation is abundant. Most of the low-elevation areas are sparsely covered with shrubs and grasses; large
8 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
areas of sagebrush are in the north, and creosote bush is in the south. At intermediate elevations, juniper and pinyon woodland is common in the isolated mountains of Nevada and in large areas of Utah, Colorado, Arizona, and New Mexico. Forests of pine and fir trees are common in the higher elevations of the mountains.
Topography and orographic influences. Mountains with high topographic relief influence the quantity and distribution of precipitation and runoff. As moisture moves into the study area from the north, west, or south, mountains act as barriers and cause an uneven areal distribution of precipita tion. Along the windward side of mountains,
LLI CC
a in
o oLLIinCC LLI Q-t- LLI LLI U.
oCDD O
LLI(3CC<I o in
LLI Q_
5,000
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
o^.29 31 33 35 37 39 41
LATITUDE, IN DEGREES
43 45
Figure 3. Relation between latitude and the maximum unit-peak discharge of record at gaged sites in the southwestern United States.
Description of Methods
Table 3. Magnitude of maximum unit-peak discharge of record compared with latitude and proportions of peaks caused by thunderstorms in the southwestern United States
Averege
Latitude, in degrees
29-37
37-39
39-41
41-45
Number of sites
559
256
226
282
Maximum unit- peak discharge
of record, in cubic feet
per second per square mile
316
66
61
26
Percentage of maximum peaks of record caused by
summer thunderstorms
63
47
34
9
Percentage of entire record with peaks
caused by summer thunderstorms
60
38
22
6
moving air masses drop much of their moisture as the air is forced to ascend over the mountains. In contrast, on the leeward sides of mountains, air masses usually descend, temperatures increase, and precipitation decreases. In the study area, areas of increased precipitation and heavy runoff on wind ward sides of mountains occur in central Arizona, central New Mexico, east-central Utah, and south western Colorado. Areas of decreased precipitation and smaller runoff on leeward sides of mountains occur in most of Nevada, western Utah, and north eastern Arizona.
Topography and stream channels. The con veyance properties of stream channels are related to the slope of the channel, material constituting the bed and banks of the channel, geometry of the channel, shape and width of the natural flood plain, and the topography of the area through which the stream is flowing. The topography of the study area can be grouped into three broad categories in which the streams have similar conveyance properties. These categories are (1) mountains, (2) piedmont plains, and (3) base-level plains, plateaus, or allu vial valleys. Burkham (1988) described flood hazards for a similar classification of topography for streams in the Great Basin in California, Idaho, Nevada, Oregon, Utah, and Wyoming.
Mountainous areas typically have V-shaped valleys that are well drained and composed mostly of bedrock and colluvium. The stream channels are typically steep, scoured, and rocky. The flood plain is narrow or nonexistent. The system of stream channels in the mountains is tributary, and the peak discharge of large floods typically increases as the
drainage area increases. Much of the Colorado Plateaus province (fig. 2) has stream channels that are deeply incised into the surrounding bedrock. In these areas, the flood-runoff characteristics are simi lar to mountainous areas.
Piedmont plains are transition areas between mountains and base-level plains or plateaus. The upper elevation limit of a piedmont plain is com monly at a sharp decrease in the slope of the land surface at a mountain front. A piedmont plain consists of pediments, alluvial fans, or old-fan remnants. A pediment is an erosional surface cut on rock and usually covered with a thin layer of allu vium. The upper elevation limit of a pediment is commonly at the mountain front. Alluvial fans are composed of material deposited by streams emerg ing from mountains or pediments; thus, the upper elevation limit of alluvial fans may be at the moun tain front or at the lower part of a pediment. Alluvial fans are active where stream deposition is common and stream systems are distributary. Allu vial fans are inactive where stream deposition is less common and most stream systems are tributary. Thus, active fans are mostly depositional surfaces, and inactive fans are mostly erosional surfaces.
Floodflow on pediments commonly is confined to tributary channels separated by stable ridges that are above the level of large floods. Floodflow on active alluvial fans commonly is unconfined in a distributary system of small channels separated by low and unstable ridges that are often overtopped during large floods. The size and location of chan nels on active fans can change during flooding. In contrast, floodflow on old-fan remnants commonly
10 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
HI Q.
500
0
5,000
4,500
4,000
3,500
HI IT
O CO
IT HI Q.
OZ OoHI CO
cca! 3,000l-Hl HI U.
O
cooz
2,500
HI oIT
g 2,000 co
1,500 -
1,000 -
500 -
SITES WITH LATITUDE BETWEEN 41 AND 45 DEGREES
»i.'V J_"1 I I
SITES WITH LATITUDE BETWEEN 29 AND 41 DEGREES
2,000 4,000 6,000 8,000
SITE ELEVATION, IN FEET
10,000 12,000
Figure 4. Relation between site elevation, latitude, and maximum unit-peak discharge of record at gaged sites in the southwestern United States.
Description of Methods
UJ UJ
UJ
Ul
Ul
10,000
9,000
8,000
Ul
i 7'°°o
Ul_1 Ul
6,000
5,00028
BOUNDARY OF HIGH-ELEVATION FLOOD
30 32 34 36 38 40 42
LATITUDE, IN DEGREES
44 46
Figure 5. Estimated elevation threshold for large floods caused by thunderstorms in the south western United States.
is confined to a tributary system of incised channels.
Typical streams in base-level plains, plateaus, or alluvial valleys have a defined main channel with an adjacent flood plain. During large floods, floodwater may spill over the banks of the main channel onto the flood plain. Flood plains are commonly wide, flat, and covered with riparian vegetation or agricul tural crops. These characteristics can cause the peak discharge of large floods to decrease or attenuate, mostly because the floodflow is temporarily stored in the wide, flat, and hydraulically rough flood plains. Some streams in base-level plains, pla teaus, or alluvial valleys have small main channels, and most of the floodflow of medium and large floods spreads over wide and flat flood plains. For these streams, the peak discharge of large floods can decrease in the downstream direction even where there is a large increase in drainage area. Other streams may have enlarged channels because of lateral erosion of the channel banks and (or) downcutting of the channel bed. Some of these en trenched channels can convey large floods within the confines of vertical banks.
In a few parts of the study area, streams in base-level plains, plateaus, or alluvial valleys flow through areas of highly permeable geologic material such as limestone, basalt, or sandy alluvial bed material. Large proportional losses of flow to infil
tration can occur during the small to medium floods. Most of these areas are localized except for much of the Snake River basin in Idaho (fig. 1), which is a large area of permeable volcanic mate rial. In the Snake River basin, many streams originate in the surrounding mountains and flow onto a flat plain where the water rapidly infiltrates into the ground.
Distributary-flow areas. Throughout the study area, but especially in Nevada, western Utah, south eastern California, and southern and western Arizona, distributary-flow areas can have a large effect on the flood characteristics of streams. The magnitude of peak discharges leaving a basin can be significantly reduced in basins with distributary- flow areas. A distributary-flow area, which includes active alluvial fans, commonly occurs on piedmont plains downslope from mountains. A distributary- flow area contains a primary diffluence where floodflow in a single channel separates into two or more channels. The channels commonly remain separated and have terraces. In many distributary- flow areas, the channels divide and join over wide areas and the erratic flow paths appear to occur randomly over much of the land surface (Hjalmarson and Kemna, 1991).
In the arid southwestern United States, some of the flood-peak attenuation shown by comparison of flood-frequency relations for sites on the same
12 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
stream is related to the presence of distributary-flow areas in the intervening drainage area. An example is Brawley Wash in southern Arizona in which the 100-year peak discharge decreases from 24,100 to 20,000 ft3/s between streamflow-gaging stations 09486800 and 09487000 (see data section, flood region 13). Altar Wash (station 09486800) is a tributary to Brawley Wash (station 09487000). The gross drainage area for these two sites increases from 463 to 776 mi2 . A large percentage of the po tential intervening runoff from the mountains and pediments must traverse many distributary-flow areas. The floodflow divides and combines many times and spreads laterally over the permeable soil. Even during large floods, most of the peak dis charge in the distributary-flow areas can be lost to infiltration or attenuation.
During this study, a few streamflow-gaging sites that appeared to have unusually small quantities of peak discharge for the size of drainage area were examined and found to be on distributary stream channels. During floodflow, some of the flow was bypassing the gaged sites in other dis tributary channels. At two sites, some of the flow appeared to leave the drainage basin upstream from the site and enter an adjacent drainage system. Sites with known distributary flow that could bypass the gaging station were excluded from this study.
Distributary-flow areas can be identified on standard 7.5-minute series of USGS topographic maps, which provide much of the information needed to delineate distributary-flow areas. Bifurcat ing intermittent stream symbols on maps depict distributary-flow areas. Small wash or intermittent stream symbols that end abruptly in an area with smooth contours also may depict distributary flow. Broad areas of piedmont that are marked with the sand symbol (stippled pattern) may depict aggrad ing areas and possibly distributary flow. Relative drainage-texture domains depicted by contour- crenulation counts (small rounded upslope projection of a contour line) provide excellent clues to the type of landform and potential distributary- flow areas (Hjalmarson and Kemna, 1991). The drainage texture (spacing of the more low-order drainage channels) of active areas of distributary flow normally is uniform in the upslope direction. Smooth contours that are straight and parallel (or slightly convex pointing downstream in plan view) indicate mild relief that may result from distributary flow. Contours with relatively large and narrow
crenulations may reveal remnants of old inactive fans.
DESCRIPTION OF METHODS
Methods developed for this study to estimate flood-peak discharge for various recurrence intervals are for gaged and ungaged natural flow streams. A study site will fit into one of three cat egories (1) a gaged site, (2) a site near a gaged site on the same stream, or (3) an ungaged site. The methods and their limitations are explained in this section, and step-by-step procedures and examples of using the methods are given in the section entitled "Application of Methods."
Gaged Sites
Flood-frequency relations for gaged sites can be estimated using the relations defined in this study. In the data section at the end of the report, the top line for each station in the peak-discharge columns is the peak discharge from the station flood- frequency relation. The bottom line is a weighted estimate of the peak discharge based on the station flood-frequency relation and the regional relation. Regional regression equations are discussed in the section entitled "Ungaged Sites."
Weighted estimates are considered to be the best estimates of flood frequency at a gaged site and are used to reduce the time-sampling error that may occur in a station flood-frequency estimate. The time-sampling error is the error caused by hav ing a sample of floods that is not representative of the population of floods. Usually, the time-sampling error is decreased as the length of record at a gaged site is increased. A station with a short period of record may have a large time-sampling error because the short period of record may not repre sent the full range of potential floods at the site. At short-record sites, the observed period of record at a station has the possibility of falling within a wet or dry period, and a preponderance of unusually small or large floods may yield a significantly unrepre sentative computed flood-frequency relation. The weighted estimate of flood frequency should be a better indicator of the true values because the regression estimate is an average of the flood histo-
Description of Methods 13
ries of many gaging stations over a long period of time.
The weighting procedure used in this study weights the station flood frequency and the regres sion estimate of flood frequency by the years of record at the station and the equivalent years of record of the regression estimate (Sauer, 1974). The equivalent years of record are an expression of the accuracy of the regression relation. Thus, in a weighted estimate, the flood-frequency relation for a station with a long period of record will be given greater weight than that for a station with a short period of record. Equivalent years of record for each regression estimate were estimated using a proce dure described by Hardison (1971). The following equation was used for the weighted estimate (Sauer, 1974):
QT(w) N + E (1)
where
~T(r)
N
E
weighted discharge, in cubic feet per second, for T-year recurrence interval; station value of the discharge, in cubic feet per second, for T-year recurrence interval;regression value of the discharge, in cubic feet per second, for T-year recur rence interval;number of years of station data used to compute QT(s), and equivalent years of record for Q.jtr\-
whereQT(u)
Q
X =
(2)
peak discharge, in cubic feet per second, at ungaged site for T-year recurrence interval; weighted peak discharge, in cubic feet per second, at gaged site for T-year recurrence interval; drainage area, in square miles, at ungaged site;drainage area, in square miles, at gaged site; andexponent for each flood region as fol lows:
Flood region
Name
High-ElevationNorthwestSouth-Central IdahoNortheastEastern SierraNorthern Great BasinSouth-Central UtahFour CornersWestern ColoradoSouthern Great BasinNortheastern ArizonaCentral ArizonaSouthern ArizonaUpper Gila BasinUpper Rio Grande BasinSoutheast
E Number
123456789
10111213141516
xponent X
0.8.7.7.7.8.6.5.4.5.6.6.6.5.5.5.4
Sites Near Gaged Sites on the Same Stream
Flood-frequency relations at sites near gaged sites on the same stream can be estimated using a ratio of drainage area for the ungaged and gaged sites. The drainage-area ratio should be approxi mately between 0.5 and 1.5. Characteristics of the ungaged and gaged drainage basins need to be examined. The method for ungaged sites should be used if a large tributary stream is between the ungaged and gaged sites and the tributary basin has much different topography, geology, vegetation, and other characteristics that may affect flood magni tudes. If the basins have similar characteristics and meet the drainage-area ratio requirement, peak dis charges can be computed by the following equation:
The exponent was determined by regressing the six T-year discharges (T=2, 5, 10, 25, 50, 100) on the drainage area for each flood region and taking the average of the drainage-area exponent for the six equations. In addition to the ratio method for sites near gaged sites, if a study site is between two gaged sites, the peak discharge may be estimated by interpolation between values for the two gaged sites with allowance for major tributaries.
Ungaged Sites
Flood-frequency relations at ungaged sites can be estimated using the regional models developed in this study. The models are regression equations that use basin and climatic characteristics as explanatory
14 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
variables. The regional regression analysis is dis cussed in the section entitled "Regional Analysis."
Models
Three models were used in this study to express the relation between peak discharge and basin and climatic characteristics. The most common relation is in the multiplicative form:
QT = aAbBc . (3A)
The following linear relation is obtained by loga rithmic transformation:
log<2T = loga + blogA + clogfi + ... , (3fi)
whereQT = peak discharge, in cubic feet per sec
ond, for T-year recurrence interval; A and B = explanatory variables; and a,b,c = regression coefficients.
Throughout the study area, drainage area is the most significant explanatory variable and is used as the first explanatory variable in all regional models. In a few parts of the study area, however, the rela tion between the logarithm of QT and the logarithm of drainage area is not linear as is expressed in equation 3fi. In those areas, therefore, another model was used in which drainage area is trans formed to produce a linear relation. The following equations perform that function:
QT = lOta+WVKUA-^ (4A)
or the logarithmic transformation:
log<2T = a + bAREAx + clogB + ... , (4B)
where AREA = drainage area;
B = other basin or climatic characteristic;and
x - exponent for AREA for which the rela tion is made linear.
The third model used in the study is another method of accounting for a nonlinear relation. In this case, the nonlinear relation is between the re sidual from the QT and AREA relation and a second
explanatory variable. The following equations were used to transform the second explanatory variable to yield a linear equation:
QT = aAREAb(B-d)c, (5A)
or the logarithmic transformation:
loggy = loga + MogAREA + clog(B-Jj+ ..., (SB)
whered = a constant, which is less than the mini
mum value of B, for which the relation is made linear.
Explanatory Variables
For purposes of this report, six basin and cli matic characteristics are referred to as explanatory variables and are used as terms in the model equa tions. Additional explanatory variables that are described in the section entitled "Explanatory Vari ables Investigated" were considered but were not used. The six explanatory variables that were used are shown for each site in the data section. The abbreviation for each variable and method of mea suring the variable are as follows.
1. AREA is the drainage area, in square miles, and is determined by planimetering the con tributing drainage area on the largest scale topographic map available.
2. ELEV is the mean basin elevation, in feet above sea level, and is determined by placing a transparent grid over the drainage-basin area, which is drawn on the largest scale topographic map available. The elevations of a minimum of 20 equally spaced points are determined, and the average of the points is taken. As many as 100 points may be needed for large basins.
3. PREC is the mean annual precipitation, in inches, and is determined by placing a trans parent grid over an isohyetal map of mean annual precipitation. The drainage-area boundary is drawn on the map, the mean annual precipitation is determined at each grid intersection, and the values are averaged for the basin.
A single source of isohyetal maps is not available. To use the regression equations in
Description of Methods 15
this report, the mean annual precipitation should be determined using the isohyetal maps that were used to determine the values for most of the gaging stations in this study. References for large-scale maps of mean an nual precipitation that were used in most of the States are: U.S. Weather Bureau (1963) for Arizona, Colorado, New Mexico, and Utah; Rantz (1969) for California; Thomas and others (1963) for Idaho; U.S. Soil Con servation Service (1964) for Oregon; and Lowham (1988) for Wyoming.
The original isohyetal maps that were used to determine mean annual precipitation for some of the gaging stations are in the "Climates of the States" series of the U.S. Weather Bureau (1959-61). These page-size maps were developed from data from about 1931 to 1955. These maps can be used only if larger scale maps are not available.
4. EVAP is the mean annual free water-surface evaporation, in inches, and was determined for gaged sites by linear interpolation between the isolines of map 3 from Farnsworth and others (1982). The value used for the regression equations was the value at the gaged-site location; therefore, in the application of the regression equations, the study-site location should be used. To use the methods in this report, EVAP should be estimated for the study site by linear interpolation between the isolines of EVAP shown in figs. 7, 11, and 14.
5. LAT is the latitude of the gaged site, in deci mal degrees, and is determined using the largest scale topographic map available. The value used for the regression equations was the value at the gaged-site location; therefore, in the application of the regression equations, the study-site location should be used. Deci mal degrees are the minutes and seconds of the latitude converted to a decimal.
6. LONG is the longitude of the gaged site, in decimal degrees, and is determined using the largest scale topographic map available. The value used for the regression equations was the value at the gaged-site location; therefore, in the application of the regression equations, the study-site location should be used. Deci mal degrees are the minutes and seconds of the longitude converted to a decimal.
Flood Regions and Regression Equations
A single regression model for the entire study area does not adequately explain the variation in flood characteristics. The standard errors of esti mate for T-year discharges were more than 100 percent for all attempted single models. In addition, these single models were biased in certain parts of the study area. The study area, therefore, was divided into 16 flood regions, and separate regres sion equations were developed for each region. Use of the 16 flood regions removes some of the vari ability in the system that is not explained by available explanatory variables and thus makes the subsequent equations simpler and more accurate. The flood regions were delineated on the basis of the magnitudes of floods, meteorologic cause of floods (snowmelt, summer thunderstorms, or cyclonic rainfall), elevation of the sites, and geo graphic patterns in residuals from the regression analysis. A consistent geographic pattern in residuals from a single study-wide relation was not discerned; therefore, an explanatory variable that could define the study-wide geographic varia tion could not be developed.
The first major stratification for the study area was for a high-elevation region that extends throughout the entire study area. The lower boundary of the region corresponds to an esti mated elevation threshold for large floods caused by thunderstorms (fig. 5). The elevation of the study site is used to determine if the site fits in the high-elevation region. The remaining 15 flood regions consist of low- to middle-elevation sites (table 4, figs. 6-16) where nearly all boundaries are drainage divides. The exceptions are the boundary between Regions 6 and 10, which is at 37° latitude, and part of the boundary between Region 8 and Regions 6 and 7 in southern Utah.
Information about the 16 flood regions includes the number of gaging stations, time of year of peak discharges, and an index to the many tables and figures that describe the regions (table 4). The num ber of gaging-station records used for most flood regions is less than the number of available gaging- station records within the region (table 4, figs. 17 49). Flood-frequency relations could not be defined for some sites because the data were unreliable or because a three-parameter distribution did not appear to adequately fit the plot of annual peaks in the records. Also, a few outlier stations
16 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
were deleted from the regression analysis, and some sites had missing values for explanatory variables and thus were not used. The deleted outliers may be different from the majority of sites by random chance, or occasionally their basin or channel char acteristics are much different from the majority of sites. For Regions 6, 10, 11, and 16 where the hybrid method was used, data for all available gag ing stations were used (table 4).
The regression equations developed for estimat ing regional flood-frequency relations (tables 5-20) are applicable for sites with characteristics that fall within the range of explanatory variables for the gaged sites that were used to develop the equations. Plots of the explanatory variables used for the regional equations were prepared for each flood region. Figure numbers for the plots are listed in table 4. The plots depict a cloud of common values. The regression equations are applicable to sites with characteristics that fall within this cloud of common values. The predictive errors of the equations in crease with distance from the mean values of the explanatory variables, and errors are unknown and probably are quite large beyond the cloud of com mon values.
The regression equations are most applicable to sites with drainage areas of less than about 200 mi2 . Gaged sites used in the analysis were selected to ensure a reliable sample to define regional rela tions for basins of up to about 200 mi 2 . Basins between 200 mi2 and the limits of the cloud of common values for each region were used to better define the relation between peak discharge and drainage area for the small basins. The regression equations are for basins of less than 200 mi2 ; judi cious use of the equations should be made for basins between 200 mi 2 and the limits of the cloud of common values.
The peak discharges estimated from the regional models can be compared with the relations between the maximum peak discharge of record and drain age area for gaged sites in each flood region and for the entire study area (fig. 17). Figure numbers of the relations for each flood region are listed in table 4. All available gaged sites in a region are shown on these plots. Three relations are drawn on most plots for the flood regions an envelope curve for maximum peak discharge of record for the gaging stations used in the entire study area, the relation between the 100-year peak discharge and drainage
area for the entire low- to middle-elevation study area (Regions 2-16), and the relation between the 100-year peak discharge and drainage area com puted for the region. For regional relations with multiple variables, the 100-year peak-discharge relations are for mean values of the variables used in addition to drainage area. Effects of these addi tional variables are not accounted for in the regional relations between the 100-year peak dis charge and drainage area; therefore, the plots of these regression lines may not appear to fit the data.
The envelope curve for the entire study area (fig. 17) is a measure of the maximum potential floodflow at gaged sites in the southwestern United States. The envelope curves for each flood region are similar measures for each region. The curves are based on data at the gaged sites used in this study and do not include miscellaneous data col lected at ungaged sites or data at gaged sites with less than 10 years of record. A few extreme floods at ungaged sites in the study area are above the envelope curves and may have been debris flows. Thus, the envelope curves represent only the data used for the statistical analysis.
The plots of maximum peak discharge of record for gaging stations in the study area were compared to three other envelope curves of maximum mea sured peak discharges. The envelope curve for this study, however, is based on gaging-station records of 10 or more years, and the three other envelope curves are based on measured peak discharges from all available records. Costa (1987) developed an envelope curve for maximum rainfall-runoff floods measured in the United States. The envelope curve for data in this study (fig. 17) is about 40 percent of the magnitude of the curve in Costa (1987) for drainage basins of less than about 100 mi2 . For the larger drainage areas, the envelope curve in this study is only about 20 percent of the magnitude of the curve in Costa (1987). Crippen and Bue (1977) developed envelope curves for 17 regions of the United States. Regions 14 and 16 in Crippen and Bue (1977) are entirely inside the study area of this report. Regions 7, 8, and 11 of this study are com parable to Crippen and Bue's region 14 (1977; see Colorado Plateaus, fig. 2, this report), and Regions 6, 10, 12, 13, 14, and 16 are comparable to Crippen and Bue's region 16 (1977; see Basin and Range, fig. 2, this report). For region 14 of Crippen and Bue (1977), the envelope curve for the applicable
Description of Methods 17
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18 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
data in this study has a similar magnitude as the curve for region 14. The magnitude of the envelope curve for region 16 in Crippen and Bue (1977) is similar to the magnitude of the envelope curve in Costa (1987). The envelope curve for the applicable data in this study and the envelope curve for region 16 in Crippen and Bue (1977), therefore, have the same relation as described for this study and Costa (1987).
Transition Zones
At most ungaged sites in the study area, flood- frequency relations can be estimated using the single set of equations for the flood region in which the site is located. When a site is near a regional boundary, however, a weighted estimate of peak discharge may be more appropriate. Computed peak discharges from the equations of two adjacent regions may be quite different for a site near a boundary. The method of dividing the study area into flood regions requires distinct boundaries, but the boundaries do not necessarily imply a distinct change in flood characteristics. Instead of the dis tinct boundaries, transition zones can be used to provide smooth transitions across boundaries.
Two transition zones are defined in this report where methods are provided to estimate weighted flood-frequency relations (1) sites with a drainage area in two low- to middle-elevation regions and (2) sites in a low- to middle-elevation flood region with an elevation that is near the boundary of the high- elevation region. A third transition zone is where a site is near a regional boundary, but the drainage area is entirely in one region. Characteristics of the drainage basin of the study site may need to be compared with the general characteristics of the adjacent flood regions. If the site is similar to both regions, a straight average of computed peak dis charges from both regions may be appropriate.
Weighted flood-frequency relations should be used when the drainage area of the study site is in two low- to middle-elevation regions. The peak discharge should be computed using the equations for both regions. The basin and climatic characteris tics for the entire basin should be used in the computations for both regions. A weighted peak discharge is then computed using the percentage of the drainage area in each region. The following equation should be used:
W AREA
whereQT(W) = weighted discharge, in cubic feet per
second, for 7-year recurrence interval; gy,, - discharge for region (a), in cubic feet
per second, for 7-year recurrence interval;
QT,b) = discharge for region (&), in cubic feetper second, for T-year recurrence interval;
AREA/a) = drainage area in region (a), in squaremiles;
AREA^ = drainage area in region (&), in squaremiles; and
AREA = total drainage area in both regions, insquare miles.
Weighted flood-frequency relations should be used for sites in a low- to middle-elevation flood region when the elevation of the study site is near the boundary of the high-elevation region. A transi tion zone is defined as a zone of elevation that starts at the boundary of the high-elevation region and extends 700 ft below that boundary (fig. 5). South of 41° latitude, all study sites with an elevation between 6,800 and 7,500 ft are in the transition zone. North of 41° latitude, the zone is at progressively lower elevations as the latitude increases (fig. 5). In the transition zone, dis charge should be computed using the equation for the low- to middle-elevation region in which the site is located and by using the equation for the high-elevation region. The characteristics of the entire basin should be used in both computations, and then a weighted discharge should be com puted on the basis of the study-site elevation as follows:
B-E B-E
where
Q-T(h) =
E =
weighted discharge, in cubic feet per second, for T-year recurrence interval; discharge from the low- to middle- elevation region, in cubic feet per second, for 7-year recurrence interval; discharge from the high-elevation region, in cubic feet per second, for 7-year recurrence interval; elevation of the study site, in feet; and
Description of Methods 19
B - elevation of the lower boundary of thehigh-elevation region, in feet (fig. 5).
The weighted discharges are thus close to the low- to middle-elevation models near the lower part of the transition zone and close to the high- elevation model near the upper part of the transition zone.
Excluded Streams and Distributary-Flow Areas
Regional flood-frequency relations that are based on a large sample of flood peaks and explanatory variables are assumed to represent most of the streams in the study area. A few streams, however, have variables that are not represented, and regional relations should not be used for these streams. Streams that may not be represented by the regional relations include (1) streams with basin and climatic characteristics that are outside the range of explanatory variables, (2) streams in basins that have large areas of highly permeable rocks, (3) ungaged streams in some regions that have less base flow than nearby gaged streams,(4) streams with channel characteristics that cause a large quantity of floodflow attenuation, and(5) streams that are part of a system of distributary channels or that have a drainage that includes large distributary-flow areas.
Streams that have basin characteristics that are outside the range of explanatory variables for the gaged sites used to develop the regional relations are not represented by the regional flood-frequency relations. Also, some potentially important basin characteristics are not defined. For example, surficial geology is an important characteristic that affects floodflow, but it is not included specifically as an explanatory variable in the regional relations. The regional relations reflect some large regional differences in geologic conditions, but local effects of surficial geology may not be reflected.
Drainage basins that have large areas of highly permeable rocks are not represented in the regional relations. Only a few stations used in the relations were in basins draining highly permeable rocks such as limestone or volcanic rocks. Large amounts of floodflow can be lost along stream channels that traverse these areas. The quantity of water lost to infiltration appears to vary from stream reach to stream reach, and regional relations of peak dis
charge for such streams cannot be defined using available explanatory variables. The Snake River Plain in Idaho is an example of a large continuous area for which regional relations were not devel oped (fig. 10).
For some regions, the sample of gaged streams may be biased because streams that are gaged tend to be those that have more base flow. In the arid west, the network of streamflow- gaging stations was established because of water- supply needs and issues, and flood issues were and continue to be of secondary concern. In some regions, such as central Arizona, most of the gaged sites are on streams that have a large base flow in basins that have a similar aspect. These gaged basins may have storm characteris tics, such as orographic effects, that are different from nearby ungaged basins with a different aspect. In places, the sample of gaged sites used for this study was defined by water-supply needs, and the sample may not represent flood character istics for nearby ungaged streams.
Streams with channel characteristics that cause a large amount of floodflow attenuation are not represented in the regional relations. Such streams may have small channels and large, hydraulically rough flood plains. Drainage basins that have large distributary-flow areas are not represented in the regional relations. The magnitude of peak dis charges leaving a basin can be significantly reduced in areas with distributary flow.
Alternative Methods
The methods described in this study apply to streams with flow unaffected by anthropogenic works and are based on a sample of gaging stations on streams draining areas of less than 2,000 mi2 . Existing flood-frequency relations in the referenced reports can be used for sites with flow affected by anthropogenic works and for large drainage areas. In the unusual situations where the described methods of this report do not apply, many alternative methods can be used to estimate flood- frequency relations. Most of the alternative methods require an estimate of rainfall intensity for a specific probability. Runoff characteristics for the estimate of rainfall are then estimated using a deterministic model of rainfall-runoff relations
20 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Stetes
(Crawford and Linsley, 1966; Leavesley and others, 1983), an empirical relation such as the rational method (Chow, 1964, p. 14-6 to 14-8), or a model such as the unit hydrograph (Chow, 1964, p. 14-13 to 14-34). A nationwide comparison of alternative methods for estimating flood-frequency relations on ungaged streams is provided by the U.S. Water Resources Council (1981).
The channel-geometry method is applicable to many natural stream channels; however, a visit to the study site is required. Estimates from channel- geometry methods are based on the concept that the size and shape of an alluvial channel are measures of the discharge of water and transport of sediment. Reports describing channel-geometry methods within the study area are shown in table 1. A re view of channel-geometry methods was made by Wahl (1984).
The methods presented in this report, the rainfall-runoff models, and the channel-geometry method are applicable to streams on tributary sys tems of channels. Floodflow is much more difficult to estimate on alluvial fans or distributary-flow areas (Dawdy, 1979; McGinn, 1980; Hjalmarson and Kemna, 1991).
Assumptions and Limitations of Methods
It is important to recognize the assumptions and limitations inherent in the statistical methods used to estimate flood-frequency relations. The flood- information transfer method used in this study for most regions has two main components. Flood- frequency relations are first estimated from the series of annual peak discharges at streamflow- gaging stations. Information then is transferred to ungaged sites by relating the peak discharges at specific recurrence intervals at gaged sites to explanatory variables by using multiple-regression techniques. In this approach, the flood-frequency relations determined for gaged sites are the founda tion.
Flood-Frequency Relations at Gaged Sites
Flood-frequency relations at gaged sites were estimated by fitting a probability distribution to the gaging-station records. In this study, the log- Pearson Type III distribution was fit to the data using the method of moments. The assumptions for applying a probability distribution to a set of
streamflow records are that the record at the gaged site is representative of the population of floods that can occur at the site, and that the annual peak dis charges are independent, homogeneous, and random.
The population of annual peak discharges is defined as the whole class of possible occurrences of annual peak discharges in the past, present, and future. A sample is used that is an observed part of the population to describe and make inferences about this population. The annual peak discharges generally are independent and random; however, homogeneity may be a problem and needs careful examination. The factors that affect the annual peak discharges generally should remain constant to assure a homogeneous sample or population. Thus, watershed conditions should be constant during the period of record for the sample and for the period for which flood frequency is to be estimated. Cover conditions of the watershed such as vegetation, soil, and extent of urban areas generally should be constant. The streamflow regime should not change significantly because of urbanization, channeliza tion, or construction of reservoirs, diversions, and levees. If all the assumptions are met, the relations of magnitude and frequency for past floods are assumed to be applicable to future floods and there-fore are used to predict the future magnitude and frequency of floods.
An unbiased and accurate record of annual peak discharges is needed for a flood-frequency analysis made on the basis of gaged data. Methods used in this study to ensure record accuracy include analy sis of the accuracy of measurements of peak discharges, addition of historical and paleoflood information to records, comparisons of systematic records and frequency estimates to envelope curves of maximum measured floods, comparison of records to droughts and wet periods, and sta- tionarity analysis.
Regional Flood-Frequency Relations
The multiple-regression method that was used for determination of most of the regional flood- frequency relations provides a means of estimating design-flood magnitudes at ungaged sites. The regional relations are based on a sample of gaged streams that is assumed to represent the population of flood events and streams in the study area. Thus,
Description of Methods 21
49 °<T-_ 120° "--116 ~r~
C A112°
- T
N A D A 108°-T "" r~ "i
104°-- -j---
I
10C
_ «. 1 1
45'
I NEBRASKA
O R A D O I KANSAS
0 100 MILES
0 100 KILOMETERS
GULF OF MEXICO
EXPLANATION
STUDY AREA
MAJOR BASIN DIVIDE
FLOOD-REGION NUMBER Region name listed in table 4
NOTE: Flood Region 1 consists of high-elevation areas throughout the study area
Figure 6. Flood regions in the study area.
22 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
113 110°
36
50 MILES
50 KILOMETERS
11
BOUNDARY OF FLOODREGIONS
FLOOD-REGION NUMBER
EXPLANATION
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
60 LINE OF EQUAL FREE WATER- SURFACE EVAPORATION Interval 5 inches (Farnsworth and others, 1982)
STREAMFLOW-G AGING STATION
A Station relation defined
A Station relation undefined
Figure 7. Flood regions in Arizona.
Description of Methods 23
any errors or uncertainty contained in the estimates sites. A potentially large problem with an individualof flood-frequency relations from records of gaged relation at a gaged site is the time-sampling error,sites are transferred to the estimates for ungaged which is the error caused by having a sample that
BOUNDARY OF FLOODREGIONS
FLOOD-REGION NUMBER
EXPLANATION
INTERSTATE HIGHWAY
JMJ= U.S. HIGHWAY STATE HIGHWAY
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Figure 8A. Flood regions in California.
24 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
does not represent the population of floods at the site. This time-sampling error, however, is partially reduced by the combining and averaging of station flood-frequency relations in the regression method.
Flood magnitudes at ungaged sites in Regions 6, 10, 11, and 16 were estimated using a new hybrid method. As in the multiple-regression method, the hybrid regional relations are based on a sample of gaged streams that is assumed to represent the population of flood events and streams in the study area. The hybrid regional relations are subject to a time-sampling error associated with the sample of gaged sites used to represent the regional popula tion of floods.
Use of regional relations with values of explanatory variables outside the range of the sample that is used to define the relations can result in unreliable estimates of peak discharge. Average standard errors of prediction for the regional equa tions in this report are for the average of the explanatory variables. For values of variables that are much different from the average, errors may be much greater than the average standard error of prediction. For explanatory variables with a large exponent, small departures from the average value of the variable can have corresponding large errors. Application of a regional relation where two or more of the values of the explanatory variables are
120° 119°
36
50 MILES
50 KILOMETERS
Figure 8B. Flood regions in California.
Description of Methods 25
50 MILES
BOUNDARY OF FLOODREGIONS
FLOOD-REGION NUMBER
50 KILOMETERS
EXPLANATION
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Figure 9. Flood regions in Colorado.
26 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
50 KILOMETERS
EXPLANATION
SNAKE RIVER PLAIN Flood msesa frequency undefined
BOUNDARY OF FLOOD REGIONS
3 FLOOD-REGION NUMBER
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-G AGING STATION
A Station relation defined
A Station relation undefined
Figure 10. Flood regions in Idaho.
Description of Methods 27
109° 108° 107' 106° 105° 104° 103°
16
BOUNDARY OF FLOODREGIONS
FLOOD-REGION NUMBER
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
EXPLANATION
50- LINE OF EQUAL FREE WATER- SURFACE EVAPORATION Interval 5 inches (Farnsworth and others, 1982)
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Figure 11. Flood regions in New Mexico.
28 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
120° 119'118 115°
50 MILES
50 KILOMETERS
EXPLANATION
BOUNDARY OF FLOODREGIONS
FLOOD-REGION NUMBER
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Figure 12. Flood regions in Nevada.
Description of Methods 29
50 KILOMETERS
BOUNDARY OF FLOODREGIONS
2 FLOOD-REGION NUMBER
EXPLANATION
INTERSTATE HIGHWAY
=L20J= U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-G AGING STATION
A Station relation defined
A Station relation undefined
Figure 13. Flood regions in Oregon.
30 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
EXPLANATION
BOUNDARY OF FLOODREGIONS
16 FLOOD-REGION NUMBER
INTERSTATE HIGHWAY
-so
J87J U.S. HIGHWAY
STATE HIGHWAY Not portrayed beyond flood region
Figure 14. Flood regions in Texas.
LINE OF EQUAL FREE WATER- SURFACE EVAPORATION Interval 2 and inches (Farnsworth and others, 1982)
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Description of Methods 31
113° 112°
50 MILES
BOUNDARY OF FLOODREGIONS
7 FLOOD-REGION NUMBER
Figure 15. Flood regions in Utah.
0 50 KILOMETERS
EXPLANATION
=-<|5> INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
32 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
110° 109' 108° 106°
50 MILES I
50 KILOMETERS
BOUNDARY OF FLOOD REGIONS
4 FLOOD-REGION NUMBER
EXPLANATION
INTERSTATE HIGHWAY
U.S. HIGHWAY
STATE HIGHWAY
STREAMFLOW-GAGING STATION
A Station relation defined
A Station relation undefined
Figure 16. Flood regions in Wyoming.
Description of Methods 33
1,000,000
100,000
o oLUenCC LU Q.
o mz> o
C3 IT< oen
LU Q.
10,000
1,000
100
100 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 17. Relation between maximum peak discharge of record and drainage area for gaged sites in the study area.
near the limits of the range of sample values may result in a combination of values that is outside the sample range. Such extrapolations are subject to large potential errors, and the results may be mis leading.
Predicted floods from regression models are an average for an entire area; therefore, a particular site may have smaller or larger floods depending on basin, climatic, and channel characteristics that are not used in the regression equations. The user of the regression models should be aware of the character istics of the basin to which the model is applied. Because of the averaging characteristic of the regression models in this study, another limitation of their application is that estimated peak dis charges near many of the flood-region boundaries may be quite different using two adjacent regional models.
APPLICATION OF METHODS
To estimate flood-frequency relations at a study site, the user should use the following steps. Examples are given for sites in one region and for sites near flood-region boundaries.
1. Using latitude and elevation of the study site, determine if the study site is in High- Elevation Region 1 or in a low- to middle- elevation region (fig. 5). If the study site is in a low- to middle-elevation region, determine the flood region of the study site using fig ures 6-16.
2. Using the flood region and the data section, determine if the study site is on a gaged stream.
34 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
3. If the study site is at a gaged site, use the listed weighted flood-frequency values for that site in the data section.
4. If the study site is near a gaged site on the same stream, use the method described in the section that follows entitled "Sites Near Gaged Sites on the Same Stream."
5. If the study site is on an ungaged stream, use the method described in the section that fol lows entitled "Ungaged Sites."
Sites Near Gaged Sites on the Same Stream
Flood-frequency relations for sites near gaged sites on the same stream can be computed using the drainage-area ratio of ungaged site to gaged site. If the ratio is between 0.5 and 1.5 and the ungaged and gaged sites are draining similar basins, equation 2 should be used to compute the required peak dis charges. If the ratio is outside that range or the basins are significantly different, the method for ungaged sites should be used. Flood-frequency rela tions for sites between gaged sites on the same stream can be determined by interpolating between values of drainage areas for gaged sites in the data section.
The following is an example of determination of the 10- and 100-year peak discharges for the Pecos River in New Mexico at an ungaged site. The drainage area (A u) is 165 mi2 . In the data section, the station, 08378500 Pecos River near Pecos, New Mexico (drainage area Ag=l&9 mi2), is in High- Elevation Region 1 and is downstream from the study site.
1. Check that the drainage-area ratio A u/A g is between 0.5 and 1.5. That ratio is as follows:
= 1,480 ft3/s, and <2 1nZ = 3,250 ft3/s.
" 8 189 mi 2
which meets the ratio requirement. Equation 2 is used.
where= weighted peak discharge from the
data section, and x = 0.8 for the High-Elevation Region
1.2. Obtain the weighted peak discharges at the
gaged site from the data section:
3. Compute the peak discharges at the ungaged site:
=1 '330ft3/S'
= 2'920 ft /s -
The computed 1 00- year peak discharge appears reasonable in comparison to the plot of maximum peak discharge of record and drainage area for the region (fig. 19).
Ungaged Sites
Flood-frequency relations at ungaged sites can be determined using one of the following proce dures, depending on the location of the site and its relation to the flood-region boundaries. The first procedure is for sites with a drainage area in one region. The second procedure is for sites with a drainage area in two low- to middle-elevation regions. The third procedure is for sites in a low- to middle-elevation region with an elevation that is within 700 ft of the lower boundary of High- Elevation Region 1.
Use the following step-by-step procedure to compute flood-frequency relations at ungaged sites.
1. If the drainage area of the study site isentirely within one flood region, compute the required information for one region. If the drainage area of the study site is in two low- to middle-elevation regions or if the elevation of the study site is within 700 ft of the lower boundary of the High-Elevation Region 1, a weighted flood-frequency relation is needed and the required information for the two adjacent regions should be computed.
2. Use table 4 and the flood region(s) of the study site to find the tables and figures con taining the required information. The explanatory variables required for each region are in column 3. The numbers of the tables of equations for estimating regional
Description of Methods 35
in ino
Q.
O 111 cc
z. z.
< 111
40
30
20
10
CLOUD OF COMMON VALUES
I*
:r :r«*
st«iiiii
4
fllillim '
i f
MM IT
»*
1*
0 0.1 10 100 1,000 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 18. Joint distribution of mean annual precipitation and drainage area for gaged sites in the High-Elevation Region 1.
Table 5. Generalized least-squares regression equations for estimating regional flood-frequency relations for the High-Elevation Region 1
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; PREC, mean annual precipitation, in inches. Data were based on 165 stations, Average number of years of systematic record is 28]
Recurrence interval, in years
2
5
10
25
50
100
Equation
2=0.1 24 ARE A0845PREC 144
g=0.629AREA° 807PREC ' ' 2
e=1.43AREA°-786PREC°-958
0=3.08AREAOJ68PREC° 8 "
e=4.75AREA°-758PREC°-732
e=6.78AREA°-750PREC°-668
Average standard error of prediction,
in percent
59
52
48
46
46
46
Equivalent years of record
0.16
.62
1.34
2.50
3.37
4.19
flood-frequency relations are in column 4. Figures showing the relation between maxi mum peak discharges of record and drainage area are in column 5. Figures showing plots of explanatory variables and their cloud of common values are in column 6. Compute the required explanatory variables using the methods described on pages 15 and 16.Determine if the values of explanatory vari ables are within the cloud(s) of common
values shown in the figures listed in column 6 of table 4. If they are within the cloud(s) of common values, then proceed to step 5. If they are outside the cloud(s), the methods are not defined for the study site, and the meth ods should be used with extreme caution. Use the equations for the appropriate region(s) (tables 5-20) to compute the flood- frequency relation at the study site. See the following examples for sites using equations for one region or two regions.
36 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
o o111 (n cc ui o_I-LU 111 U.
O CO
O
111 CD CE <I O c/
111Q_
100,000
10,000
1,000
100
100.1 10 100 1,000 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 19. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the High-Elevation Region 1.
Site with a Drainage Area in One Flood Region
The first example is the use of the regression equations with the model described by equation 3. Determine the peak discharges for recurrence inter vals of 10 and 100 years for an ungaged site in the Northeast Region 4 (fig. 6, tables 4 and 8). The required basin characteristics are drainage area (AREA), in square miles, and mean basin elevation (ELEV), in feet. Using the procedures described in the section entitled "Explanatory Variables," the drainage area is computed as 35 mi2 and the mean basin elevation is 7,500 ft. The drainage area and mean basin elevation are in the cloud of common values for the region (fig. 24). The characteristics are inserted into the appropriate equations as fol lows:
610 = 1.26(AREA)°-674(ELEV/1,000) L64 =
1.26(35)°-674(7.5) L64 = 377 ft3/s,
and
Q 100 = 11.8(AREA)°-662(ELEV/1,000)0 - 835 =
11.8(35)°-662(7.5)0- 835 = 668 ft3/s.
The computed 100-year peak discharge appears reasonable in comparison to the plot of maximum peak discharge of record and drainage area for the region (fig. 25).
The second example is for the use of the re gression equations with the model described by equation 4. Determine the peak discharges for recurrence intervals of 50 and 100 years for an ungaged site in Central Arizona Region 12 (fig. 6, tables 4 and 16). The required basin character-
Application of Methods 37
LU LU
12,000
10,000
8,000
5 6,000
< 4,000 CD
<LU
2,000
0.1
CLOUD OF COMMON VALUES
11 I10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 20. Joint distribution of mean basin elevation and drainage area for gaged sites in the Northwest Region 2.
Table 6. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Northwest Region 2
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 108 stations. Average number of years of systematic record is 26]
Recurrence Interval, In yeara
2
5
10
25
50
100
Equation
e=13.1AREA°-713
e=22.4AREA°'723
e=55.7AREA°-727(ELEV/l > 000)-°- 353
e=84.7AREA°-737(ELEV/l,000)-°-438
e=113AREAa746(ELEV/l,000)-°-511
e=148AREAa752(ELEV/l,000)-°-584
Average standard error of
prediction, In percent
72
66
61
61
64
68
Equivalent years of record
0.96
1.80
3.07
4.64
5.47
6.05
istics are drainage area (AREA), in square miles, and mean basin elevation (ELEV), in feet. Using the procedures in the section "Explanatory Vari ables," the drainage area is computed as 110 mi 2 , and the mean basin elevation is 5,900 ft. The drainage area and mean basin elevation are in the cloud of common values for the region (fig. 40).
The characteristics are inserted into the appro priate equations as follows:
10(7.36-4.17(110)-°-08 ) (5 90)-0.440 = ft3 /s>
and= 10(6.55-3.17(AREAr°.H)(ELEV/1?000)-0.454 =
90)-o.454 = ft3 /s
38 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
o oLLIen enLLIo.
oCODo
LLIC3 CC<o en0
10,000
1,000
100
10
^,s^~&*
\*m>I
0.1 10 100 1,000 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 21. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northwest Region 2.
The computed 100-year peak discharge appears reasonable in comparison to the plot of maximum- peak discharge of record and drainage area for the region (fig. 41).
Site with a Drainage Area in Two Low- to Middle-Elevation Flood Regions
A hypothetical study site has a drainage area in the Northern and Southern Great Basin Regions (Regions 6 and 10). Thus, an averaging procedure based on the percentage of the drainage area in each region should be used. The peak discharges are estimated for each region as if the drainage area is entirely in one region. Then, a weighted peak dis charge is estimated using equation 6.
An example for the use of regression equations for two regions is as follows. Determine the peak discharges for recurrence intervals of 10 and 100 years for an ungaged site with a drainage area in Northern Great Basin Region 6 and Southern Great Basin Region 10 (fig. 6, tables 4, 10, and 14). The required basin and climatic characteristics are drain age area (AREA), in square miles, and mean basin elevation (ELEV), in feet. Using the procedures discussed in "Explanatory Variables," the basin and climatic characteristics are computed as 57 mi2 for drainage area and 6,500 ft for mean basin elevation. The drainage area and mean basin elevation are within the cloud of common values for Region 6 (fig. 29), and the drainage area is within the range of drainage area for Region 10 (fig. 37). On the topographic map, the drainage area is bisected by
Application of Methods 39
03IIIIO z 40
z"
O
£ 30HD_
O
S£ 20
< 10
<HIS
n
CLOUD OF COMMON
.ij^S^ -
.it]
,.g*|||;i
.";'i :i : :. : :" T^-?:'/! :::. :rS. :::^:
>*!: ifS
j$.m K\s [
a H*
it»:
is
,%
: ^:
; : !E!E
: Si!
: :':
::;: -
i;y
U i
SB
««:
*«5if;
»; :,.,
&?>«?. !: :,,
vgiy...
%ijSfc* S:| S'lKii
islHII lilt;;;
:>" «; iiifS :- iS««!';rS:
if ft f l|il!h:
Si:li;|i«!lr»«- : ' ;: '
,,,.,,! , ,,,,,,,! , ,,,,-,! , ,,,,,,,! i , ,,,,,,,
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 22. Joint distribution of mean annual precipitation and drainage area for gaged sites in the South-Central Idaho Region 3.
Table 7. Generalized least-squares regression equations for estimating regional flood-frequency relations for the South-Central Idaho Region 3
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles: PREC, mean annual precipitation, in inches. Data were based on 35 stations. Average number of years of systematic record is 32]
Recurrence interval, in yeara
2
5
10
25
50
100
Equation
(2=0.444AREA°-649PREC1 15
e=1.21AREA°-639PREC0995
e=1.99AREA°-633PREC°-924
e=3.37AREA0627PREC°-849
(2=4.70AREA°-625PREC0- 802
Q=6.42AREA°-621 PREC0757
Average standard error of prediction,
in percent
86
83
80
78
77
78
Equivalent years of record
0.29
.49
.77
1.23
1.57
1.92
the regional boundary at 37° latitude. The northern region includes 21 mi2, and the southern region includes 36 mi2 . The basin and climatic characteris tics are inserted into the appropriate regional equations to obtain estimates of 7-year discharges for each region. Then, equation 6 is used to obtain weighted estimates of 7-year discharges. For the Northern Great Basin Region 6, the equations are as follows:
<2 10 = 590(AREA)°-62(ELEV/1,000)-L6 =
590(57)a62(6.5)- L6 = 362 ft3/s,
and
<2 100 = 20,000(AREA)a51 (ELEV/l,000)-2- 3 =
20,000(57)a51(6.5r2 - 3 = 2,120 ft3/s.
For the Southern Great Basin Region 10, the equations are as follows:
40 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
Qz o oUJco tr
oCD
o
I o coQ
10,000
1,000
100
10 11 110.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 23. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the South-Central Idaho Region 3.
<2 10 = 200(AREA)°-62 = 200(57)°-62 = 2,450 ft3/s,
and
fi 100 = 850(AREA)°-69 = 850(57)°-69 = 13,800 ft3 s.
The computed 100-year peak discharges for Regions 6 and 10 appear reasonable in comparison to the plots of maximum peak discharge of record and drainage area for the regions (figs. 30, 37).
Estimates of weighted peak discharges using equation 6 are as follows:
(362x21 ) + (2,450x36) 57 3 tt /s '
(2,120x21) + (13,800x36)57
3 rt /s
and
Low- to Middle-Elevation Site Near the High- Elevation Flood Region
A hypothetical study site is in a low- to middle- elevation flood region but the site elevation is within 700 ft of the boundary of High-Elevation Region 1 (fig. 5). Thus, an averaging procedure based on the relation between the elevation of the study site and the 700-foot transition zone should be used. The peak discharges are estimated for each region as if the drainage area is entirely in one region. Then, a weighted peak discharge is esti mated using equation 7.
Application of Mathods 41
12,000
H 10,000LU LU
8,000
gi-
S 6,000
< 4,000 CO
2,000
0.1Li.
10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 24. Joint distribution of mean basin elevation and drainage area for gaged sites in the Northeast Region 4.
Table 8. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Northeast Region 4
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 108 stations. Average number of years of systematic record is 28]
Recurrence Interval, In
years
2
5
10
25
50
100
Equation
2=0.0405 AREA°-701 (ELEV/1,000)2-91
e=0.408AREA°-683(ELEV/l,000)2-05
e=1.26AREAa674(ELEV/l,000)1 - 64
Q=3 .74 AREAa667(ELE V/l .OOO) 1 M
g=7.04AJlEA0664(ELEV/l >000) 1 - 02
!2=11.8AREA0662(ELEV/1,000)0835
Aversge stsndsrd error of prediction,
In percent
64
57
53
51
52
53
Equlvslent years of record
0.39
.95
1.76
3.02
3.89
4.65
An example for the use of regression equations for High-Elevation Region 1 and a low- to middle- elevation region is as follows. Determine the peak discharges for recurrence intervals of 2 and 50 years for an ungaged site in the Four Corners Region 8 with a site elevation of 7,100 ft (fig. 6). The site elevation is within 700 ft of the boundary of High-Elevation Region 1, which is 7,500 ft in the latitudes of Region 8 (figs. 5, 6). The regression
equations for Region 1 are in table 5, and the equa tions for Region 8 are in table 12. The required basin and climatic characteristics are drainage area (AREA), in square miles; mean basin elevation (ELEV), in feet; and mean annual precipitation (PREC), in inches. Using the procedures in the sec tion "Explanatory Variables," the drainage area is computed as 45 mi2 , the mean basin elevation is 8,900 ft, and the mean annual precipitation is 28 in.
42 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Stetes
1,000,000
100,000
o oUJinDC UJ D_I-
oCD
O
UJ C5CE<
O 05Q
UJ Q.
10,000
1,000
100
10 I0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 25. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northeast Region 4.
The drainage area and mean annual precipitation are in the cloud of common values for Region 1 (fig. 18), and the drainage area and mean basin elevation are in the cloud of common values for Region 8 (fig. 33).
Basin and climatic characteristics are inserted into the appropriate regional equations to obtain estimates of T-year discharges for each region. Then, equation 7 is used to obtain weighted esti mates of T-year discharges. For the Four Corners Region 8, the equations are as follows:
Q2 = 598(AREA)°-501 (ELEV/1,000)- L02 =
598(45)0 - 501 (8.90)- L02 = 433 ft3 /s ,
and
Q5Q = 16,000(AREA)a390(ELEV/l,000)- L54 =
16,000(45)°-390(8.90)- 1 - 54 = 2,440 ft3 /s .
For High-Elevation Region 1, the equations are as follows:
Q2 = 0.124(AREA)°- 845 (PREC) 1 -44 =
0.124(45)0 - 845 (28) L44 = 375 ft3 /s ,
and
£50 = 4.75(AREA)°-758 (PREC)°-732 =
4.75(45)°-758 (28)°- 732 = 975 ft3 /s .
The computed 50-year peak discharges for Regions 1 and 8 appear reasonable in comparison to
Application of Methods 43
co 39 mccC3mQ
- 38mQ
H<_l
37
oc
0
... .... ' ' :-.::> ':&:: S '- ife?: : '-.-
VMVmigAm? ' ';:; 1 ; ;:': ;!.:,.,.£ j-j££; ; ;.;:^f sjiji.!: ':;Jrr ,: ; ;:;> ; :
::: ' :; ;;;. ; ; : ; . ; ;.:':;"#:;. ;->>:^> :.;.;,>-:
"i-sj'iAsiilWiirJ ::iiii>!?:i|.;,|!l!|
"piiii Jjjj^v
1 1 10
iPf
f!
If: :> ?
1
1 1
i!
ii^is1!"
si
, i100
, :; 1:«|;:'; ; .
i - ffihii'rii
i* ill"
Ifeff -
F
\CLOUD OFCOMMON VALUES
1,000 10,C
DRAINAGE AREA, IN SQUARE MILES
Figure 26. Joint distribution of latitude and drainage area for gaged sites in the Eastern Sierras Region 5.
inLU
<> mmz co00
<1115
12,000
10,000
8,000
6,000
4,000
2,000
0.1
CLOUD OF COMMON VALUES
18Niiil!lli|l|ll||
10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 27. Joint distribution of mean basin elevation and drainage area for gaged sites in the Eastern Sierras Region 5.
the plots of maximum peak discharge of record and and drainage area for the two regions (figs. 19, 34).
Estimates of weighted peak discharges using equation 7 are as follows:
7,500-7,100,
7.500-7.100
700/
7,500-7,100
975(1-
700
7,500-7,100
700)= 1,810 ft3/s
44 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Stetes
Table 9. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Eastern Sierras Region 5
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet; LAT, latitude of site, in decimal degrees. Data were based on 37 stations. Average number of years of systematic record is 31]
Recurrence interval, in years
2
5
10
25
50
100
Equation
e=0.0333AREAa853(ELEV/l,000)2- 68 [(LAT-28)/10]4- 1
!2=2.42AREA0- 823(ELEV/l,000)L01 [(LAT-28)/10]4- 1
fi=28.0AREA°-826[(LAT-28)/10]4- 3
e=426AREA°-812(ELEV/l,OOOruo[(LAT-28)/10]4-3
e=2,030AREA°-798(ELEV/l > OOOrL71 [(LAT-28)/10] 4-4
2=7,000 AREA°-782(ELEV/l,000)-zl8[(LAT-28)/10]4-6
Average standard errcr of prediction,
In percent
135
101
84
87
91
95
Equivalent years of record
0.21
.73
1.69
2.62
3.26
3.80
1,000,000
o oLU 03
trLUo_I-Ltl111 u.OCO
O
o03
Q
^
sCL
100,000
IO,000
1,000
100
10
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
100-YEAR PEAK-DISCHARGE RELATION FOR REGION
1±_ ll_0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 28. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Eastern Sierras Region 5.
Applicaticn of Methods 45
ID ID
Zo
111z03< COz
12,000
10,000
8,000
5 6,000
4,000
2,000
0.1
\CLOUD OF COMMON VALUES
I10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 29. Joint distribution of mean basin elevation and drainage area for gaged sites in the Northern Great Basin Region 6.
Table 10. Hybrid equations for estimating regional flood-frequency relations for the Northern Great Basin Region 6
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 80 stations. Dashes indicate no data. Average number of years of systematic record is 19. Estimated average standard error of regression for the hybrid method includes much of the within-station residual variance and therefore is not comparable to standard error of estimate from an ordinary least-squares regression. See section entitled "Hybrid Method" for explanation of error]
Recurrence interval, in years
2
5
10
25
50
100
Equation
Q=0
j2=32AREAa80(ELEV/l,000)-°-66
e=590AREAa62(ELEV/l,000)-L6
e=3,200AREA°-62(ELEV/l,OOOr2- 1
2=5,300 AREAa64(ELEV/l,OOOrzle=20,OOOAREA°-51 (ELEV/l,000)-2- 3
Estimatedaverage
standard error of regresaion,
in log units
--
1.47
1.12
.796
1.10
1.84
Equivalent years of record
--
0.233
.748
2.52
1.75
.794
ANALYSIS OF GAGING-STATION RECORDS
Gaging-station records of annual peak discharges are the foundation of the data base used in this study. Records throughout the study area were
selected and examined for accuracy and the required assumptions for a statistical analysis. Flood-frequency relations were computed using statistical and graphical analyses. The final best-fit individual relations then were used to develop regional flood-frequency relations using the meth-
46 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
o o 111 coIT 111D_ Hlil 111 u_O OQ
o
111 CD IT <
O coQ
111 D_
100,000
10,000
1,000
100
10
* * ^
. . * .
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 30. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northern Great Basin Region 6.
ods described in the following section "Regional Analysis."
Records Used
Records for 1,323 gaging stations in the USGS peak-flow file were used in this analysis. The records contain the maximum peak discharge for each water year (October 1-September 30). Gaging stations selected for this study (1) are mostly within the study-area boundary, (2) have 10 years or more of systematic record, (3) have annual peak dis charges that were not significantly affected by
regulation or diversions, and (4) are on a system of tributary streams.
The systematic gaging-station records are for data collected by the USGS during 1890 to 1986. Systematic data are the result of regular observa tions over a period of time. The systematic records range in length from 10 to 83 years, and approxi mately 32,500 station years of data are included in the 1,323 records. The period of record was extended at 119 sites with historic floods and at 5 sites with paleofloods. A historic flood or paleoflood is the largest in a known period beyond the systematic record. Historic-flood records ranged from 12 to 200 years, and paleoflood records ranged from 280 to 2,100 years. The historic and paleoflood information added about 7,500 station
Application of Methods 47
Table 11. Generalized least-squares regression equations for estimating regional flood-frequency relations for the South-Central Utah Region 7
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 28 stations. Average number of years of systematic record is 23]
Recurrence t d d f Equivalentintervel, in Equation s an ar . e .r years of
years . record 7 percent
2 £>=0.0150AREAOM7(ELEV/l,000)-3i6 56 0.25
5 £>=0.306AREA05go(ELEV/l,OOOr222 45 1.56
10 2=1.25AREA()526(ELEV/1,000)- |W 45 3.07
25 £=122 AREA" 440 49 4.60
50 2=183AREA(U9° 53 5.27
100 0=264AREA" 344 59 5.68
12,000
H 10,000UlUlu_z
8,000
O1-
£ 6,000
Ul
zC/3< 4,000CO
zUl
S 2,000
0 - -
I I I I ] I I I I I
-f-ii^ "'&iti( 3%;*',:,, ,.
:fii;!llilllplltll|»
"ri i!llCLOUD OF COMMON VALUES
- -
"
I I I I
0.1 1 10 100 1,000 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 31. Joint distribution of mean basin elevation and drainage area for gaged sites in the South-Central Utah Region 7.
years for a total of 40,000 station years in the data base.
The gaging stations are fairly well distributed in the study area (fig. 50). Several gaging stations outside the study-area boundary in northeastern New Mexico and west-central Texas were included in the analysis to add some information to that part of the study area. The stations are most dense in the humid mountainous areas and least dense in the arid desert areas. The average systematic record length for all sites is 25 years and ranges from 19 to 35 years for the 16 flood
regions defined in this study. Record length tends to increase with drainage area because most early data- collection efforts were concentrated in the larger basins for water-supply purposes (table 21).
The annual peak discharges, in cubic feet per second, are converted to common (base 10) logarithms for the flood-frequency analyses in this study. The average of the mean peak discharges in each record is 2.3 log units, the average standard deviation is 0.45, and the average skew coefficient is 0.028.
48 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
o o111 enen
LLI LLI LLO m3 o
I O enQ
111a.
10,000
1,000
100
10
$%s&. ".
110.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 32. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the South-Central Utah Region 7.
Stationarity and Trend Tests
One of the assumptions needed for a statistical flood-frequency analysis is that the series of annual peak discharges is homogeneous. One aspect of a homogeneous series is that the annual peaks should be stationary over time. The factors that affect the annual peak discharges generally should remain constant during the period of record for the sample and for the period of time for which flood fre quency is to be estimated.
The time series of annual peak discharges were examined for long-term changes using the two- sided nonparametric Kendall tau statistical test. The 340 gaging stations that had at least 30 years of record were used for the test. At least 30 years of record was considered necessary for reliable detec
tion of trends. Eighty-two percent of the stations had no trend significant at the 5-percent level (oc=0.05), and about an equal number of stations had positive and negative trends (table 22). The computed trend apparently is independent of drain age area because stations that had a wide range of drainage area had no trend or equal amounts of increasing and decreasing trends.
The results indicate no significant trend in time for annual peak discharge at the gaging stations in the study area. A nonuniform geographic distribu tion of computed trends, however, indicates a systematic effect. A negative trend of decreasing magnitudes of annual peaks for several gaging sta tions was detected in the southeastern part of the study area. Fourteen percent of the selected stations in Colorado and New Mexico have a decreasing
Analysis of Gaging-Station Records 49
LJJ LJJ
12,000
10,000
8,000
5 6,000
< 4,000 co
2,000
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 33. Joint distribution of mean basin elevation and drainage area for gaged sites in the Four Corners Region 8.
Table 12. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Four Corners Region 8
[Equation; Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 108 stations. Average number of years of systematic record is 27]
Recurrence interval, in years
2
5
10
25
50
100
Equation
e=598AREA°-501 (ELEV/l,OOOrL02
2=2,620 AREA°-449(ELEV/1,000)-1 -28
e=5,310AREA°-425(ELEV/l,000)-1 -40
2=10,500 AREA°-403(ELEV/l,OOOrL49
e=16,OOOAREA°-390(ELEV/l,000)-L54
(2=23 ,300 AREA0-377(ELEV/l,OOOrL59
Average standard error cf prediction,
in percent
72
62
57
54
53
53
Equivsient years cf record
0.37
1.35
2.88
5.45
7.45
9.28
trend, and only 2 percent of the selected stations have an increasing trend. In the northern part of the study area, 27 percent of the selected stations in Oregon, Idaho, and Wyoming have an increasing trend, and no decreasing trends were detected at any stations.
Changes of the physical conditions of the basins in the northern and southeastern part of the study area that may have caused changes in the magni tude of flood peaks were unknown for this study. If the computed trends are related to climatic varia
tion, extrapolation of the trend to the future is considered tenuous and beyond the scope of this study. An analysis of possible trends and climatic variability for the Santa Cruz River in southern Arizona showed that these factors introduce uncer tainty in flood-frequency estimates (Webb and Betancourt, 1992). Adjustment of the computed flood-frequency relations was not made because there was no known physical condition in the basins that could explain the computed trends and because
50 Methods for Estimating Magnitude and Frequency of Flccds in the Southwestern United States
1,000,000 r
Q z o oUlenIT UJ Q_I- UJ UJ
oCD
O
UJC5IT <
O o)
100,000
10,000
1,000
100
10
100-YEAR PEAK-DISCHARGE RELATION FOR REGION
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
110.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 34. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Four Corners Region 8.
trends were detected at only a few of the stations in the northern and southeastern parts of the study area.
Flood-Frequency Analyses
Analyses were made to determine flood- frequency relations at 1,323 gaging stations. The relation of annual peak discharge to exceedance probability, or to recurrence interval, is referred to as a flood-frequency relation or curve. Exceedance probability is the chance that a flood will equal or exceed a given magnitude in any year. Recurrence interval is the reciprocal of the exceedance prob ability and is the average number of years between exceedances.
In the flood-frequency analyses, peak-discharge records were analyzed by mathematical fitting and graphical analysis. Some adjustments were made to obtain the best fit of the flood-frequency relations to the data. Individual frequency relations were defined for 1,059 sites. Relations were not defined for 264 sites because of inadequate samples and poor fits of the relations to the data. A small sample of gaging-station records with mixed populations was analyzed to estimate the effect of such popula tions on the frequency relations. A detailed analysis was done to estimate the regional relations of skew coefficient for the study area. The final flood- frequency relations presented in this study reflect the individual adjustments and the incorporation of the new information on regional skew coefficient.
Analysis of Gaging-Station Records 51
HI HI
12,000
10,000
8,000
5 6,000
HI 2 CO
4,000
2,000
CLOUD OF COMMON VALUES
I0.1 10 100 1,000
DRAINAGE AREA, IN SQUARE MILES
10,000
Figure 35. Joint distribution of mean basin elevation and drainage area for gaged sites in the Western Colorado Region 9.
Table 13. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Western Colorado Region 9
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 43 stations. Average number of years of systematic record is 28]
Recurrence interval, in
years
2
5
IO
25
50
100
Equation
g=0.0204AREA0 - 606(ELEV/I,OOOr3 - 5
Q=0. 1 8 1 AREA0 ' 5 ' 5 ( ELE VI I .OOO)' 2 - 9
g= 1 . 1 8 AREA°'4XX(ELEV/ 1 ,000r2 ' 2
^.S^AREA^ELEV/KOOO)-'-'
e=248AREA°-44 ')
£=292AREA°-444
Averege standard error of
prediction, in percent
68
55
52
53
57
59
Equivalent years of record
0.14
.77
1.70
2.81
3.36
3.94
The log-Pearson Type III probability distribu tion (LPIII) and the method of moments were used to define flood-frequency relations for gaging- station records (Interagency Advisory Committee on Water Data, 1982). In this method, the series of annual floods at a site is assumed to represent a random sample from a single distribution whose characteristics do not change with time. The LPIII is a three-parameter generalization of the log-
normal statistical distribution that provides sufficient flexibility to approximate many observed flood distributions. To fit the LPIII to a sample of data using the method of moments, the annual floods are converted to logarithms and three statis tics are computed mean, standard deviation, and skew coefficient. The mean and standard deviation of the sample define the position and slope of a plot of the data on log-normal probability paper. Log-
52 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000 r
OO LLJinCE LU 0.H LU LU U.O CD
O
LU O CE <
O CO Q
LU Q_
100,000
10,000
1,000
100
10
100-YEAR-PEAK * DISCHARGE RELATION
FOR REGION
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
I , I I
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 36. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Western Colorado Region 9.
normal data plot as a straight line, and LP1II data plot as a curve with the skew coefficient defining the amount and sense of curvature.
Detailed evaluations of the computed flood- frequency relations were made by visual examination of the fit of the LPIII probability distribution to the plotted annual peak discharges. The Cunnane plot ting position formula was used to plot the data on log-normal probability paper. The Cunnane plotting position essentially is unbiased and distribution free and provides a satisfactory visual comparison between the computed flood-frequency relation and the plotted peak discharges (Cunnane, 1978).
The shape of flood-frequency relations for sites is assumed to have limitations. The expected slope of the relations is positive because peak discharge increases with decreasing probability of occurrence.
The expected shape of a relation in log-probability space is a straight line or a smooth curve with no sharp breaks or discontinuities; therefore, a three- component LPIII distribution was used to fit relations. Also the fitted relation is expected to visually agree with the plotted data; for example, a persistent departure of the smaller annual peaks from the fitted relation is not considered a satisfac tory fit.
The reliability of station flood-frequency rela tions was assessed by how well the computed relations fit the plotted peak discharges, by the presence or absence of outliers, and by the shape of the distribution of the plotted peaks. The assess ment showed that 264 sites have a poor fit of the computed relation to the plotted peaks, odd- appearing plotted peaks, and usually a large vari-
Analysis of Gaging-Station Records 53
Table 14. Hybrid equations for estimating regional flood-frequency relations for the Southern Great Basin Region 10
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles. Data were based on 104 stations. Average number of years of systematic record is 21. Estimated average standard error of regression for the hybrid method includes much of the within-station residual variance and therefore is not comparable to standard error of estimate from an ordinary least-squares regression. See section entitled "Hybrid Method" for explanation of error]
Recurrence interval, in years
2
5
10
25
50
100
Equation
e=12AREA°-58
e=85AREA°-59
e=200AREA°-62
e=400AREAft65
<2=590AREA°-67
<2=850AREA069
Estimatedaverage
standard error of regression,
in log units
1.14
.602
.675
.949
.928
1.23
Equivalent yeara of record
0.618
3.13
3.45
2.49
3.22
2.22
500,000
100,000
Q
o o111 U)oc
111111
oCO
111 C3 DC < I Oen o
LLIQ.
10,000
1,000
100
10
100-YEAR PEAK- X ^-DISCHARGE RELATION
. X FOR REGION
VX
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 37. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southern Great Basin Region 10.
54 Methods for Estimating Magnitude and Frequency of Floods in the Southweatern United States
ance. The peaks at many of these 264 sites that have inadequate flood-frequency relations were used in the hybrid analysis to estimate regional flood-frequency relations. The remaining 1,059 sites were judged to have adequate flood-frequency relations.
Examination of the plotted peaks found some similar characteristics that occurred in many of the records with defined relations (table 23). Thirty- eight percent of the sites had plotted peaks with the expected smooth shape of a LPIII distribution. The remaining sites had one or more departures from expected shape. Adjustments to the frequency rela tions were made for sites with low outliers (Interagency Advisory Committee on Water Data, 1982, appendix 5). When available, historical peri ods were applied to sites with high outliers. Other departures from expectation, such as sites with discontinuities (jumps) or sharp breaks (doglegs) in the plotted peaks were coded, but no adjustments were made.
The percentage of gaged sites with low dis charge thresholds, high outliers, doglegs, and jumps in their plotted peaks was compared with the basin and climatic characteristics of the sites (table 24). The gaged sites were placed into three incremental classes of the characteristics, and an analysis of variance (ANOVA) was performed to test if there is a significant difference in the percentages between the three classes. The ANOVA was performed by coding the gaged sites with a 1 if the attribute is present and a 0 if the attribute is absent. Thus, the mean of the 1's and O's in each class of basin or climatic characteristic is the percentage of the attributes in each class. The following three sec tions discuss the results of these comparisons.
Low Outliers and Low-Discharge Threshold
Low outliers can have an adverse effect on computed flood-frequency relations for gaged sites by causing a large negative skew coefficient that can distort the frequency relation by flattening the upper end of the relation. Low outliers are small peak discharges that depart from the low end of a fitted flood-frequency relation. In addition, zero- flow years in gaged records are low outliers. For many sites, the departure of the small peaks from the fitted relation may be related to characteristics of the basin or stream channel. This type of depar ture should be called a hydrologic low outlier to
emphasize that it is defined by hydrologic consider ations rather than by statistical tests. Hydrologic low outliers often define a different relation than the midrange and large peaks. A peak-discharge record with characteristics of a hydrologic low outlier may be evidence that the smaller peaks are from a different flood population than the larger peaks. Meteorologic processes and watershed char acteristics may affect small flood peaks differently than large peaks.
Small peaks that are identified as low outli ers using a statistical test and zero-flow years are truncated, and a conditional probability adjustment is made to obtain the final frequency relation in the procedure recommended by the Interagency Advi sory Committee on Water Data (1982, p. 17-19, appendix 5). The statistical procedure detects the smallest peaks; however, many small peaks that depart from the fitted relation are not identified as outliers. In this study, therefore, a low-discharge threshold was used to adjust for those small peaks that depart from the fitted relation but are not de tected by the statistical test. Application of this low-discharge threshold also used the conditional probability adjustment to obtain the final frequency relation. The statistical procedure (Interagency Advisory Committee on Water Data, 1982) general ly is successful in making appropriate adjustments for low outliers; however, computed results need to be examined for hydrologic low outliers if the pro cedure is not successful.
The low-discharge threshold was applied to sites primarily on the basis of the visual fit of the computed relation to annual peak discharges using the Cunnane plotting positions. At many sites, the plot of annual peak discharges has a segment of small peaks that curves steeply downward. The low-discharge threshold was commonly set at a sharp downward break in the relation and always was set at a probability greater than 0.7, which is a recurrence interval of less than 1.4 years. The low- discharge threshold was applied to 48 percent of the sites with defined flood-frequency relations (table 23), and many of those sites have a statistical low outlier. The stations with an applied low-discharge threshold are identified in the data section by a 1 in the L column under the heading "Relation Char acteristic." With few exceptions, the use of the low-discharge threshold resulted in better fits between the relations and the plotted peak dis charges.
Analysis of Gaging-Station Records 55
coLUI
O
CC OQ-
<
Z
80
70 -
60 -
400.1
i±_
CLOUD OF COMMON VALUES
Sills J!»iS;ltil|ftliSSftirtiiB
J_u_10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 38. Joint distribution of mean annual evaporation and drainage area for gaged sites in the Northeastern Arizona Region 11.
Table 15. Hybrid equations for estimating regional flood-frequency relations for the Northeastern Arizona Region 11
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; EVAP, mean annual evaporation, in inches. Data were based on 46 stations. Average number of years of systematic record is 20. Estimated average standard error of regression for the hybrid method includes much of the within-station residual variance and therefore is not comparable to standard error of estimate from an ordinary least-squares regression. See section entitled "Hybrid Method" for explanation of error]
Recurrence Interval, in years
2
5
10
25
50
100
Equation
g=26AREA°-62
e=130AREA°-56
e=0.10AREA° 52EVAP2-°
e=0.17AREA°-52EVAP2-°
e=0.24AREA°-54EVAP20
2=0.27 AREAa58EVAP20
Estimatedaverage
standard error cf regression,
in log units
0.609
.309
.296
.191
.294
.863
Equivalent years of record
0.428
2.79
4.63
17.1
9.20
1.32
Another method used to select the appropriate low-discharge threshold was to examine the effect on skew coefficient and T-year discharges as suc cessive increments of peaks were truncated. The threshold was selected when computed skew coeffi cient and 7-year discharge stabilized (changed less than about 1 percent). At a few sites with a depar
ture of the smaller peaks from the fitted relation, the application of the low-discharge threshold did not result in a satisfactory fit. As the threshold was successively raised to the point of departure, a new fitted relation was computed and a new departure of additional peaks with an apparent higher threshold occurred. Relations for these
56 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
Qzo o
cc 1110.
CD
o
111CDcr< I oCO Q
1110.
10,000
1,000
100
10 , I 110.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 39. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Northeastern Arizona Region 11.
sites had a negative skew coefficient, and the skew coefficient would not stabilize as the threshold was successively increased. For these sites, the lower peaks may be a part of the entire population of peaks, and no threshold was used. The unadjusted computed relation that was used, however, did not appear to be an ideal fit to the smaller peaks.
In this study, the interest is on the midrange and larger peaks of a sample (2- to 100-year floods). Using the method of truncation with a low- discharge threshold at a recurrence interval of less than 1.4 years, the magnitude and frequency of the midrange and larger peaks are used to fit the fre quency relation. The existence and frequency of the small peaks are used for the conditional probability adjustment; however, the magnitude, which does not fit the relation defined by the other peaks, is not used.
A geographic pattern is not apparent in the dis tribution of sites with a low-discharge threshold (fig. 51). The percentage of sites with an applied low-discharge threshold was compared with basin and climatic characteristics (table 24). In general, low-discharge thresholds were used at more sites in arid areas in the southern latitudes. The sites were at lower elevations, had smaller amounts of mean annual precipitation, and had larger amounts of mean annual evaporation. Many intermittent and ephemeral streams in the southwestern United States have characteristics that indicate a low- discharge threshold. Plots of samples of annual peaks at many of these streams have a segment of small peaks that curves steeply downward. The cause of this steep lower segment in the plotted peaks often is the large infiltration losses of the smaller annual peaks.
Analysis of Gaging-Station Records 57
UJ UJ
O
UJ
zto
<UJ
12,000
10,000
8,000
6,000
4,000
2,000
CLOUD OF COMMON VALUES
0.1 10 100 1,000 10,000
DRAINAGE AREA, IN SQUARE MILES
Figure 40. Joint distribution of mean basin elevation and drainage area for gaged sites in the Central Arizona Region 12.
Table 16. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Central Arizona Region 12
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 68 stations. Average number of years of systematic record is 21]
Recurrence interval, In
yeara
2
5
10
25
50
100
Equation
2=41.1AREA°'529
2=238AREA°-587(ELEV/l )OOOr°-358
2=479 AREAa661 (ELEV/l,OOOr°-398
2=942 AREA°-530(ELEV/1 ,000)"° 383
G=10(7.3^.17AREA^-08)(ELEy/1000)-0.440
G=10(6.55-3.17AREA-°- 11 )(ELEV/1)000)^).454
Average stsndard error of prediction,
in percent
105
68
52
40
37
39
Equivalent years of record
0.23
1.90
6.24
17.8
27.5
32.1
The following two examples of gaging-station records with low outliers show the effect on computed relations of using all peaks in the record compared with using the low-discharge threshold. At streamflow-gaging station 09480000, Santa Cruz River near Lochiel, Arizona, the 100-year peak discharge for an unadjusted relation is 5,200 ft3/s, which is about one-half of the discharge for the relation with the low- discharge threshold adjustment (fig. 52). The
unadjusted relation is far below the two largest annual peaks. No known physical characteristic of the drain age basin can explain the flattening of the flood-frequency relation for large floods. Also, the unadjusted relation has a 100-year discharge that is about one-quarter of the discharge using a regional estimation procedure (Reich, 1988, p. 30). The use of the low-discharge threshold of 450 ft3/s, which is greater than 5 of the 41 annual peaks, results in a
58 Methoda for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000 r
100,000
o oLUincc LU0.H LU LU LL
OCD D O
LUOCC<
O CO
Q
LU Q.
10,000
1,000
100
10
* -^ <>> v " t-U1 ' «- '*&&**'
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 41. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Central Arizona Region 12.
flood-frequency relation that better fits the data using a Cunnane plotting position. The default statistical adjustment for this station produced a satisfactory relation for the 2- to 100-year floods (Interagency Advisory Committee on Water Data, 1982, appendix 5); however, the computed skew coefficient was con sidered too negative, and the low-discharge threshold of 450 ft3/s was used.
At streamflow-gaging station 09513910, New River near Glendale, Arizona, use of a low-discharge threshold of 2,500 ft3/s results in a change in the 100- year peak discharge from 75,100 ft3/s to 58,800 ft3/s (fig. 53). The channel bed is permeable sand, and a large percentage of small peaks is lost to infiltration. No peaks were below the statistical threshold for the unadjusted relation, and six peaks were below the low- discharge threshold of 2,500 ft3/s for the adjusted relation. The adjusted relation more closely fits the
large annual peaks, including the historic peak that was outside the period of systematic record.
High Outliers and Historical Periods
High outliers can have a significant effect on com puted flood-frequency relations at gaged sites. High outliers are large peak discharges that depart from the high end of a fitted flood-frequency relation. Gaging- station records with high outliers usually have a large positive skew coefficient and a large variance. Many large peaks that are part of the systematic record at gaging stations are high outliers because the large peak is the maximum for an extended period of time that is much longer than the period of systematic record. Flood-frequency relations fit to those samples often have large computed discharges for the infre-
Analysis of Gaging-Station Records 59
Table 17. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Southern Arizona Region 13
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles. Data were based on 73 stations. Average number of years of systematic record is 21]
Recurrence interval, In
years
2
5
10
25
50
100
Equation
g_jQ(6.38-4.29AREA"fl-06)
g=1 Q(5.78-3.31AREA-°-08)
g=10(5.68-3.02AREA~°-09)
g=10(5.64-Z78AREA-°- 10)
G=10(5.57-2.59AREA^- 11 )
g=10(5.52-Z42AREA^-l 2)
Average standard error of prediction,
in percent
57
40
37
39
43
48
Equivalent years of record
2.0
6.25
11.1
15.0
15.9
16.1
1,000,000 r
100,000
o o HI to cc HI 0.I-LLI
oCD
HI CD cc <o ena
HI0.
10,000
1,000
100
10
100-YEAR PEAK-DISCHARGE RELATION FOR REGION
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
I I0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 42. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southern Arizona Region 13.
60 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
quent floods and may not represent the true flood population. Large peaks that are considered high outliers can be adjusted by use of a historical period for which the peak is a maximum.
Seventeen percent, or 178, of the gaged sites with defined flood-frequency relations had high outliers (table 23). The stations with a high outlier are identified in the data section by a 1 in the H column under the heading "Relation Characteristic." Most of these outliers were statistically identified (Interagency Advisory Committee on Water Data, 1982, p. 17-19); however, about 10 percent of the outliers were defined visually by the observed departure from the fitted flood-frequency relation. Available information that often defines an extended period during which the high-outlier floods are known to be maximum flows are included in the analysis. For example, if the outlier peak was the largest known flood for the past 75 years on the basis of reliable newspaper accounts, a historical period of 75 years would be used. A his torical period was estimated for 124 (12 percent) gaged sites.
No pattern is apparent in the geographic distri bution of gaging stations with high outliers (fig. 54). The percentage of high outliers in gaging- station records was compared to basin and climatic characteristics (table 24). Only drainage area had a significant relation (cc=0.02), and that has no linear trend as seen by the percentage of stations for the three strata of drainage areas (table 24). High out liers, therefore, appear to be random and unrelated to some of the more important variables that are related to the magnitudes of floods.
Use of historical flood information, such as the historical or extended period outside the period of systematic record for outlier peaks, commonly is assumed to add information and improve the accu racy of flood-frequency relations. In this study, the exclusion of the outlier peaks would have had a significant effect on the regional relations. If the high outlier peaks are excluded, the average com puted 100-year discharge for the 178 records is 38 percent smaller than the average computed 100-year discharge with the high outliers included. The over all effects of the high outliers and the use of historical periods on the regional analysis were not investigated. Clearly, if the high outliers were excluded from the 178 records, estimated regional 100-year discharges would be smaller than the esti mated discharges using the high outliers; however.
the magnitude of the effect on the regional relations is unknown. The high outliers were not excluded because of the recommendation to retain high out liers by the Interagency Advisory Committee on Water Data (1982, p. 17).
Sharp Breaks or Discontinuities in Plotted Peaks
For most gaged sites in the study area, the series of annual peak discharges displayed on log-normal probability paper were either a straight line or a smooth curve. Two departures from this expected shape were identified in about 16 percent of the sites with defined flood-frequency relations. These sites had sharp breaks or discontinuities in the plot of peak discharges. One hundred sites had plotted peaks with a sharp break, or "dogleg," appearance (table 23). A site with a sharp break in the plotted peaks has a lower and upper segment; the lower segment generally has a steeper slope than the upper segment. Thus, a sharp break is shown at the intersection of the two slopes. Sixty-eight sites had plotted peaks with a substantial discontinuity, or "jump," in the plotted peak discharges where two or more segments are displaced vertically (table 23, fig. 55). The stations with a dogleg or jump in the plotted peaks are identified in the data section by a 1 in the D column under the heading "Relation Characteristic."
When plotted peaks have a dogleg shape and only a few small peaks are included in the lower segment, the small peaks can be truncated with the low-discharge threshold and a uniform relation can be fit to the data. The 100 sites classified as dogleg, however, either have the break in plotted peaks at a recurrence interval greater than 1.4 years, which is the limit for truncation with low-discharge thresh old that was defined in this study, or a successive incremental application of a low-discharge thresh old did not change the dogleg shape.
The cause of doglegs and jumps may be related to physical characteristics of the stream channel or drainage basin, types of storms causing floods, and instability of small sample sizes. Because of the nature of statistical samples, some of the log-normal probability plots for sites with short records might be expected to substantially depart from an expected smoother curve. As the sample size is increased, smoother plots might be expected. There fore, the frequency of doglegs and jumps was compared with record length, but no significant relation was found for the sites in this study area.
Analysis of Gaging-Station Records 61
Ill 111
12,000
10,000
8,000
6,000
< 4,000 CD
2,000
CLOUD OF COMMON VALUES
I I0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 43. Joint distribution of mean basin elevation and drainage area for gaged sites in the Upper Gila Basin Region 14.
Table 18. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Upper Gila Basin Region 14
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet. Data were based on 22 stations. Average number of years of systematic record is 26]
Recurrence interval, In years
2
5
10
25
50
100
Equation
(2=583AREA0- 588(ELEV/l,OOOr1 - 3
j2=618AREA0-524(ELEV/l,OOOra70
(2=361AREAa464
(2=581 AREA0-462
(2=779 AREA0'462
j2=l,010AREAa463
Average standard error of prediction,
in percent
74
63
65
63
64
66
Equivalent years of record
1.69
3.54
4.95
7.75
9.65
11.2
Dogleg shapes may be caused by attenuation of peak discharge because of stream-channel charac teristics, such as channels with bed material that have high infiltration rates, wide channels, or small channels with wide flood plains. Causes of jumps in a record may be mixed flood populations, such as floods from snowmelt or summer thunderstorms, and different flood populations caused by the differ ent effects of the watershed on small or large peaks.
No pattern is apparent in the geographic distri bution of gaging stations with doglegs and jumps
(fig. 56). The percentage of doglegs or jumps in station records was compared with basin and cli matic characteristics (table 24). The percentage of doglegs increases with increasing size of drainage area, possibly because of the increasing opportunity for attenuation of small peaks. The percentage of jumps decreases with increasing amounts of mean annual precipitation. This relation may be a func tion of mixed populations. Stations in areas with mean annual precipitation of greater than 25 in. usually have frequency relations dominated by
62 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
o oUJ COocUJ
o m:D O
10,000
1,000 -
100
10 li- J_0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 44. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Upper Gila Basin Region 14.
snowmelt runoff and little influence of mixed popu lations. The percentage of doglegs also is smaller in the middle latitudes, although the reason is unknown. Evaluation of the reliability of a flood- frequency relation fit to a gaged record with plotted peak discharges that have dogleg or jump shapes is difficult. The records, therefore, were identified and used in the regional flood-frequency analysis.
The accuracy of the annual peak-discharge data was examined for several stations with plots of peaks that had the largest departures from an expected smooth shape. For most of these stations, the stage-discharge relations used to determine peak discharges were poorly defined. Several of the ratings were for unstable channel controls, or were improperly fitted to the measurements of discharge, or the measurements of discharge used to define the
rating appeared to be inaccurate. For some stations, a discontinuity of the rating curve coincided with a discontinuity of the plot of annual peak discharges on log-normal probability paper. For other stations, the indirect measurements of peak discharge used to define the rating were made in unstable channels that probably scoured during the peak and subse quently filled when the measurement was made. For a few stations, indirect measurements of peak dis charge may have been made for debris flows. For one station, a wide inundated flood plain that was beyond the end of the measuring cableway was incorrectly assumed to have negligible flow veloc ity. Twelve stations were excluded from this study because a significant number of annual peaks were considered unreliable. Those stations are 08351500, 09279100, 09336000, 09355000, 09371000,
Analysis of Gaging-Station Records 63
107.0
en 106.5LJJ LJJ DC 05 UJ Q
Z~ 106.0UJ Q
05 z O -i 105.5
105.0
CLOUD OF COMMON VALUES,
, I0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 45. Joint distribution of longitude and drainage area for gaged sites in the Upper Rio Grande Basin Region 15.
UJ UJ
12,000
10,000
8,000
5 6,000
< 4,000 CO
<UJ
2,000
CLOUD OF fffllif COMMON VALUES
mi
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 46. Joint distribution of mean basin elevation and drainage area for gaged sites in the Upper Rio Grande Basin Region 15.
09419660, 09482000, 10241600, 10253350, 10255810, 13027500, and 13061100.
Gaged Sites with Inadequate Samples or Non-Log-Pearson Type III Distribution
Detailed investigations were made of the flood- frequency relations computed for the 1,323 gaging stationrecords. For 264 station records, a visual
examination showed extremely poor fits of the LPIII probability distribution to the plotted annual peak dis charges. Four examples of these poor fits are shown in figure 57. Flood-frequency relations computed from the data do not fit the plotted data, and the relations are much different from regional relations computed for the sites. The variability of the annual peak dis charges is extremely large at most of these stations. The average standard deviation for the 264 records
64 Methods for Estimating Msgnitude and Frequency of Floods in the Southwestern United States
Table 19. Generalized least-squares regression equations for estimating regional flood-frequency relations for the Upper Rio Grande Basin Region 15
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; ELEV, mean basin elevation, in feet; LONG, longitude of site, in decimal degrees. Data were based on 17 stations. Average number of years of systematic record is 35]
Recurrence interval, In years
2
5
10
25
50
100
Equation
g=l 8,700 AREA°-730(ELEV/1 ,000)-Z85[(LONG-99y 10)]2- 8
g=3 1 ,700AREAa645(ELEV/l ,OOOrz57[(LONG-99)/10)]2'7
2=26,000 AREA°-582(ELEV/l,OOOr2-27[(LONG-99)/10)]2-7
2=34,800 AREAa532(ELEV/l,000)-zl5[(LONG-99)/10)]2- 5
e=44,200AREAasol(ELEV/l .OOO)-2- u [(LONG-99)/10)]2-5
2=91,800 AREA°-439(ELEV/l,OOOr2-22[(LONG-99)/10)]2- 5
Average atandard error of prediction,
in percent
64
66
68
71
73
76
Equivalent years of record
0.13
.64
1.24
2.04
2.60
3.12
1,000,000 r
100,000 -
o oLLIin ccLLI Q_H LU LLI LL
O CD
O
LLI C5cc <I o en
10,000
1,000
100
10 I0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 47. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Upper Rio Grande Basin Region 15.
Analysia of Gaging-Station Records 65
Table 20. Hybrid equations for estimating regional flood-frequency relations for the Southeast Region 16
[Equation: Q, peak discharge, in cubic feet per second; AREA, drainage area, in square miles; EVAP, mean annual evaporation, in inches. Data were based on 120 stations. Average number of years of systematic record is 30. Estimated average standard error of regression includes much of the within-station residual variance and therefore is not comparable to standard error of estimate from an ordinary least- squares regression. See section entitled "Hybrid Method" for explanation of error]
Recurrence interval, in years
2
5
10
25
50
100
Equation
j2=14AREA°-51 (EVAP-32)0- 55
Q=37AREA°-48(EVAP-32)ft63
Q=52AREAft47(EVAP-32)ft67
j2=70AREA°-48(EVAP-32)ft74
e=HOAREA°-47(EVAP-34)0-74
e=400AREA°-50(EVAP-37)0-45
Estimated average
standard error of regresaion,
In log units
0.664
.269
.177
.425
.367
.442
Equivalent yeara of record
0.410
3.77
12.6
3.20
5.38
4.54
05IIIxg 80
z Oh- 70
IT 0
< >ai 60_i <13
z 50
UJ2
dn
, , ,1111, 1 , ,,,,,,,, , ,,,,,,,
CLOUD OF ,:*«»*»<«,.COMMON VALUES ...dlllii
..».,:::: . : . ii::,,:,,: ;:::-, , ./
. ;FiMNii;^m:^»ms*iii;;p&j,,,...!f:rtir!M^PiHif
-«-IS'iHi; ;!;i->. : iff 1 :;: i' : ; i!:.;;;? Vm : '> '^ ";h:^£&:~S^m
^^ f'W^MjillfSl-ffliMHWW
>^M NWHp'W«MMKIi^^f»
*;^*|n;i;^^f|l%^!^:^ifiiiM«-:: ; j; j. : i | ;pS |||, - ' 'fy'K,, - . s;i ,;:."' : * i:: iH yM - ^TO^mii
i : I i I i i . 1 I . I i i i . i
aiisfii
:s:'f!*ia,!iiiiiiii:iii
mm.m
|;|l|i|4llsiilillIHK1|||N;I
SI *:p«f
HVESj't SE:EEE:EtEEE:E¥:JF;;.;s' :
Mlllfy.ja::ct:. i^-irr: JT <?:. ^ii-iii'..^^
^al'i^illp^fp^^p^
,,,,,, ,1 , ,,,,,, ,1 1 ,,,,,,,0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 48. Joint distribution of mean annual evaporation and drainage area for gaged sites in the Southeast Region 16.
is 0.88 log units. The average standard deviation of the 1,059 stations with defined relations is 0.37 log units. An additional problem in defining relations is a short average record length of 17 years. The relations that were com puted for the annual series of peak discharges are unreliable especially for extrapolations to the 100-year flood. The computed 95-percent confidence interval typi cally is 2 to 3 orders of magnitude for these stations.
Most of these sites that had no defined flood- frequency relations are in the most arid parts of the study area, including most of Nevada, southeastern California, and southwestern Arizona (fig. 58). Of 264 stations, 42 percent had more than 25 percent of the years with no flow, and 15 percent had more than 50 percent of the years with no flow. The procedures defined in the Inter- agency Advisory Committee on Water Data (1982,
66 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
1,000,000
100,000
o oHIin ccHIa.I- uiHI LL
OCO 3 O
HIC3 ccXo03a *:HI
O,000
1,000
100
10
100-YEARPEAK-
DISCHARGERELATION
FOR REGION"
100-YEAR PEAK-DISCHARGERELATION FOR LOW- TO
MIDDLE-ELEVATION STUDY AREA
, I
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 49. Relations between 100-year peak discharge and drainage area and plot of maximum peak discharge of record and drainage area for gaged sites in the Southeast Region 16.
p. 5-11) for computing flood-frequency relations are not recommended when more than 25 percent of a gaged record has no flow.
The percentage of gaging stations with undefined flood-frequency relations was compared to basin and climatic characteristics (table 25). Significantly more (a<0.01) undefined relations were found at sites with smaller drainage areas, sites in the lower latitudes, sites with lower elevations, sites with lower mean annual pre cipitation, and sites with higher mean annual evaporation. At the 264 undefined sites, no convincing evidence exists that the plot of annual peak discharges can be fit by the LPin probability distribution. The records may be insuffi cient in length and too unstable to define a relation. The sites, therefore, are classified as having inadequate samples or non-LPHI distribution. Flood-frequency rela tions for these sites are considered unreliable and were not used in the standard regional regression analysis. Data from many of these sites, however, were used in the
hybrid analysis, which developed regional relations for Regions 6,10,11, and 16.
Mixed Populations
More than 80 percent of the sites in the study area have a mixed population of floods. Populations of floods were identified by the time of year that the annual floods occurred. A mixed population of floods is an aggregation of floods that are caused by two or more distinct and generally independent hydrometeorologic conditions. Populations in the study area include floods caused by snowmelt, rainfall, and rainfall on snow. Rainfall is caused by summer thunderstorms, winter midlatitude- cyclonic storms, winter upper-level low-pressure systems, or tropical cyclones.
When a sample of annual peaks contains a mixed population, a single flood-frequency relation can be much
Analysis of Qaging-Station Records 67
different from a compositional relation (Webb and moments between two populations in a gaging-Betancourt, 1992). The computed differences in the station record may result in relations with abnormallymean, variance, and skew (moments) of each popu- large skew coefficients and abnormal slope changeslation cause this distortion. Differences in when plotted on log-normal probability paper
100°
45
0 100 MILES
0 100 KILOMETERS
GULF OF
MEXICO
EXPLANATION
[fIJIlll STUDY AREA
MAJOR BASIN DIVIDE
+ GAGING STATION
Figure 50. Gaging stations used in this study.
68 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
Table 21. Drainage area and years of systematic record at gaging stations in the southwestern United States
Table 23. Summary of characteristics of station flood- frequency relations in the southwestern United States
Drainage area, in aquare miles
Less than 1
1-10
10-100
100-1,000
1,000-2,000
Number of gaging stations
120
299
507
342
55
Average years of syatematic
record
16.4
17.3
23.1
34.2
37.4
Table 22. Significance of trends over time in annual peak discharges for gaging stations with at least 30 years of record in the southwestern United States
Number of gaging stations
State
Arizona.........
California .....
Colorado.......
Idaho.............
Nevada .........
NewMexico ........
Oregon... .......
Texas ............
Utah..............
Wyoming......
At least30 years of record
31
24
55
22
17
90
15
4
55
27
Posi tive
2
1
1
7
3
2
5
0
5
5
Trend
Nega tive
3
1
9
0
0
12
0
0
4
0
None
26
22
45
15
14
76
10
4
46
22
Total.. 340 31 29 280
(Interagency Advisory Committee on Water Data, 1982, p. 16). A method that can be used to account for mixed populations is the composite-probability analysis.
In a composite-probability analysis, an annual peak discharge is determined for each population and a separate flood-frequency relation is computed for each population. The relations are combined using a formula for the probability distribution of the maximum of independent random variables. The formula for computing a composite relation for two populations of floods is as follows (Crippen, 1978):
Flood-frequencycharacteristics
Smooth shape of plotted data....
Applied low-dischargethreshold....................................
Historical period used ...............
High outlier and historical
Jump (discontinuity) in plotteddata............................................
Dogleg (break in slope)in plotted data...........................
Number of
stations
399
512
178
124
152
68
100
Percentage of
stationswith
definedrelations
38
48
17
12
5
6
9
Pc(x) = PA (x) + PB(x) - PA(x)PB(x) , (8)
where= probability that the annual flood in the com
posite population will exceed x,PA(x) = probability that the annual flood in popula
tion A will exceed x, andPB(X) = probability that the annual flood in popula
tion B will exceed x.
The significance of mixed populations on the flood- frequency relations computed for sites in the study area is uncertain. At some sites with a certain combination of samples of populations, the composite relation will be significantly different from the relation computed from the annual maximum peaks (mixed population); however, at many sites, the two relations will be similar.
To estimate the significance of the mixed-population problem, composite analyses were made of many repre sentative sites with a combination of floods caused by snowmelt and floods caused by rainfall from summer thunderstorms. The snowmelt and summer thunderstorm populations were selected for analysis because that combi nation is the most common in the study area. Jarrett and Costa (1982) and Thomas (1985) found that a composite flood-frequency relation for that combination may be significantly different from the relation based on annual maximum peaks (mixed population).
Analysis of Gaging-Station Records 69
Table 24. Characteristics of station flood-frequency relations compared with basin and climatic characteristics in the southwestern United States
[ANOVA, analysis of variance significance level. The gaging stations were coded with a 1 if the attribute is present and a 0 if the attribute is not present. The mean of the 1's and O's in each class of basin or climatic characteristic is the percentage of the attributes in each class. ANOVA was performed on the three classes to test if a significant difference in means (percentages) exists between the three groups (three classes of basin or climatic characteristic). Dogleg in plotted data is indicated by a sharp break or dogleg appearance. The data fit into two segments with different slopes. Jump in plotted data is indicated by a discontinuity or jump where two or more segments are displaced vertically]
Clsss
Num ber of sta
tions
Percentage of streamflow-gaglng stations with specified chsracterlstic and ANOVA significance level
Low dis charge thres hold
ANOVAHigh
outliar ANOVA
Dogleg in
plotted data
ANOVAJump in plotted
dataANOVA
Drainage area, in square miles
Less than 50
50 to 200
More than 200
536
268
255
48
48
49
17
0.83 12 0.02
21
7
9 0.01
14
6
9
5
0.18
Latitude, in degrees
Less than 37
37 to 41
More than 41
409
404
246
53
46
45
14
.09 19 .10
18
11
6 .03
11
6
8
5
.35
Mean basin elevation, in feet
Less than 6,000
6,000 to 8,000
More than 8,000
287
382
361
55
49
43
17
.01 16 .70
18
11
11 .08
7
7
7
6
.82
Mean annual precipitation, in inches
Less than 16
16 to 25
More than 25
358
408
254
56
45
43
18
.01 16 .45
15
11
9 .17
7
8
7
3
.03
Mean annual evaporation, in inches
Less than 40
40 to 55
More than 55
383
429
247
45
47
56
16
.02 19 .42
15
9
9 .78
10
6
8
4
.10
About 50 percent of the sites in the study area have a mixed population of floods caused by snowmelt and sum mer thunderstorms. These sites occur throughout the study area mostly in an elevation zone (fig. 59) between moun tainous areas and the plains or plateau areas. Above the elevation zone, flood characteristics are dominated by snowmelt runoff; below the elevation zone, flood charac teristics are dominated by thunderstorms (McCain and Jarrett, 1976, p. 31; Thomas, 1985, p. 382). The upper- elevation limit for sites with mixed populations is near or above the previously estimated upper limit for large thun derstorm-caused floods. The elevation zone of the mixed
population in the southern latitudes is about 6,200 to 8,200 ft. In the northern latitudes, the elevation zone decreases to about 4,500 to 6,500 ft. About 35 percent of the sites in the study area are in this mixed-population elevation zone.
The elevation zone for the mixed population contains most of the sites that have the potential for significantly different composite and annual maximum flood-frequency relations. Within and near the elevation zone, 51 gaged sites with more than 20 years of record that had drainage areas that ranged from 2 to 1,100 mi2 were selected (table 26, fig. 60). Composite relations were computed for the
70 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
51 sites, which are about 14 percent of the sites in the elevation zone. Most of the sites are in northern and central New Mexico, southwestern Colorado, and Utah.
In the composite analysis, the rainfall peaks were estimated from the annual peak discharge records with peaks above a base. Missing peaks were accounted for by
using a conditional-probability adjustment. Snowmelt peaks were estimated from the same records, and peaks below the base discharge were estimated as mean daily discharges from historical records. The relations for rainfall, snowmelt, and annual maximum peaks were computed using a station skew coefficient.
CANADA 100°.024
45
--------- J, SOUTH
'. DAKOTA
0 100 KILOMETERS
f 29° N \
GULF OF \ 1
MEXICO ^
EXPLANATION
STUDY AREA
MAJOR BASIN DIVIDE
GAGING STATION
Figure 51. Gaging stations with an applied low-discharge threshold.
Analysis of Gaging-Station Records 71
The Interagency Advisory Committee on Water Data (1982) recommends weighting the station skew with a generalized skew when computing station flood-frequency relations. The purposes of this study, however, which were to compare dif ferences in composite and mixed relations, are adequately served by using station skews.
Typical differences in flood-frequency relations between sites above, in, and below the mixed- population elevation zone are described in the fol lowing three examples. A typical high-elevation site with snowmelt runoff is South Fork of Rock Creek near Hanna, Utah (09278000), which has a drainage area of 15.7 mi2 and a site elevation of 7,860 ft (fig. 61). Floods caused by snowmelt represent 90 percent of the record. In the frequency relations, the magnitude of the snowmelt relation is greater than the rainfall relation until a recurrence interval of greater than 100 years (exceedance probability of 0.01), where the curves would cross. The computed relation using the array of annual maximum peaks is adequate until the curves intersect. Thus, estimates of floods with recurrence intervals of greater than 100 years may need a composite relation.
A middle-elevation site that has a mixed popu lation of rainfall and snowmelt peaks is Big Creek near Randolph, Utah (10023000), which has a drainage area of 52.2 mi2 and a site elevation of 6,410 ft (fig. 62). The magnitudes and distributions of the rainfall and snowmelt peaks are mixed; 31 percent is caused by rainfall, and 69 percent is caused by snowmelt. About one-half of the largest 25 percent of the peaks were caused by rainfall, and the largest peak was caused by rainfall. The com posite 100-year peak is 26 percent larger than the 100-year peak based on annual maximum peaks. In this particular case, the composite relation is a more accurate depiction of the flood characteristics than the annual maximum relation.
Mill Creek near Moab, Utah (09184000), is a typical low-elevation site that has runoff domi nated by rainfall, and has a drainage area of 74.9 mi2 and a site elevation of 4,240 ft (fig. 63). Peaks caused by rainfall represent 84 percent of the record. The rainfall and composite relation are mostly coincident and are greater than the snowmelt relation for all recurrence intervals. The composite relation is not needed for such low-elevation sites.
o oLLI CO
a:LLI 0-
H LLILLI LL.
O
mID O
LLI O CC<Xo coQ
100,000
10,000
1,000
100
10
1
DRAINAGE AREA = 82.2 SQUARE MILES LENGTH OF RECORD = 38 YEARS
NO LOW DISCHARGE THRESHOLD, 100-YEAR DISCHARGE EQUALS 5,200 CUBIC FEET PER SECOND
LOW DISCHARGE THRESHOLD, 100-YEAR DISCHARGE EQUALS 11,300 CUBIC FEET PER SECOND
ANNUAL PEAK OF SYSTEMATIC RECORD
99.5 99 95 90 80 70 50 30 20 105 21 0.5 0.2
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
Figure 52. Flood-frequency relations for Santa Cruz River near Lochiel, Arizona (09480000).
72 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
The ratio of the 100-year composite peak to the 100-year annual maximum peak (mixed) for the 51 analyzed sites was used to evaluate the significance of the composite analysis. A significant difference between the composite relation and mixed relation may be at the 50- to 100-year recurrence intervals, where there is a greater influence of the potential difference in mean, variance, and skew of the two populations. The difference between relations usually is not significant for the 2- to 25-year recurrence intervals. The 100-year composite peak discharges were greater than the annual maximum peak discharges for 36 sites. Statistics for the com posite to annual maximum ratio are a mean of 1.08, a median of 1.04, and a standard deviation of 0.13. The composite 100-year peaks, although systemati cally larger than the annual maximum 100-year peaks, are only an average of 8 percent larger. This difference is considered small because of all the uncertainties inherent in flood-frequency analysis.
Jarrett (1987) examined 29 streamflow-gaging station records for mixed populations in the Colo rado River basin (part of this study area). The average ratio of composite 100-year peak to annual maximum 100-year peak for the 29 stations was
1.12 and is similar to the average ratio of 1.08 in this study. The potential problem of mixed popula tions of floods caused by rainfall and snowmelt, therefore, does not appear to be significant in the study area for estimating floods of as much as the 100-year peak discharge.
The ratio of composite to annual maximum 100-year peak discharge was compared with size of drainage area, site elevation, mean basin elevation, and geographic area. No relations were found except for geographic area, where some concentra tions of higher ratios were found in south-central Utah and northern New Mexico (fig. 60).
In conclusion, analysis of the mixed population of floods caused by snowmelt and summer thunder storms indicates that flood-frequency relations computed from the mixed populations apparently are adequate descriptions of the flood characteris tics for the 100-year flood and less. Separation of populations and a composite analysis for 51 sites did not appear to significantly change the flood- frequency relations. Sites identified with the greatest potential for a significant composite rela tion are in middle elevations. For some ungaged streams that drain basins in the middle elevations,
o oLU tO
DC LU CL
I- LU LU LL
O
o
LU C5 DC < I Oto
LU CL
100,000
10,000
1,000
100
10
1
DRAINAGE AREA = 323 SQUARE MILES LENGTH OF RECORD = 37 YEARS NO-FLOW YEARS = 4
- NO LOW-DISCHARGE THRESHOLD, 100-YEAR DISCHARGE EQUALS 75,100 CUBIC FEET PER SECOND
LOW-DISCHARGE THRESHOLD, 100-YEAR DISCHARGE EQUALS 58,800 CUBIC FEET PER SECOND
o ANNUAL PEAK OF SYSTEMATIC RECORD
+ HISTORICAL PEAK
i i i i i i99.5 99 95 90 80 1070 50 30 20
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
1 0.5 0.2
Figure 53. Flood-frequency relations for New River near Glendale, Arizona (09513910).
Analysis of Gaging-Station Racords 73
the regional relations for estimating the 100-year peak discharges at gaged sites. In this method, anpeak discharge may be about 10 percent too small. estimate of skew coefficient is required. An accu-_ . . . ,,. . rate estimate of skew coefficient is difficult toRegional Skew Coeff.c.ent obtain frf)m samples of less than 5Q data ^.^
The method of moments was used to fit the because of its sensitivity to extreme eventsLPIII probability distribution to the series of annual (Viessman and others, 1977, p. 169). Thus, skew
49°~__ 120° CANADA^r^rrr"---'----'"---!--^CANADA
108"
T
104° T
100°
45'
100 MILES
100 KILOMETERS
MEXICO
EXPLANATION
STUDY AREA
MAJOR BASIN DIVIDE
GAGING STATION
Figure 54. Gaging stations with a high outlier.
74 Methods for Estimating Magnitude and Frequancy of Floods in the Southwastern United States
coefficients estimated from the peak-discharge records in this study area are often unreliable because the average record length is 27 years and only 10 percent of the sites have more than 50 years of record. The estimate of station skew coeffi cient is improved by weighting the station skew with a
regional skew (Interagency Advisory Committee on Water Data, 1982, p. 10-12).
An analysis was made of regional skew coefficient for the series of annual peak discharges at gaging sta tions in the study area. The study hypothesis was that regional relations for skew coefficient cannot be de-
100
10
1
FEET PER SECOND 3 "8 P
0 0 -
O CQ
3 10
z
111 CD . CE 1
I Oto
° 0.1
< 1 ,000 111 a.
100
10
1
0.1 9£
: I II II I II III
: RIO DE FLAG AT HIDDEN HOLLOW ROAD AT FLAGSTAFF, ARIZONA
DRAINAGE AREA = 31.5 SQUARE MILES , LENGTH OF RECORD = 13 YEARS , *
; NO-FLOW YEARS = 2
r
i i i ^ i i i ii iii
: PENZANCE WASH NEAR JOSEPH CITY, ARIZONA 09397200
DRAINAGE AREA = 0.17 SQUARE MILES LENGTH OF RECORD = 14 YEARS * * NO-FLOW YEARS = 1
..- '
:
.
I 1 I I I 1 1 1 1 1 1
: 1 1 I II 1 II III
: TIN CAN CREEK NEAR NEEDLES, CALIFORNIA 09423400
DRAINAGE AREA = 0.04 SQUARE MILES LENGTH OF RECORD = 15 YEARS
: NO-FLOW YEARS = 4 ,
i i i i i i ill i.5 99 95 90 80 70 50 30 20 10 5 2
I I :
09400590 :
-
-
-
i i
_
-
-
i i
-
-
i i1 0.5 0.
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
Figure 55. Examples of gaging-station records with sharp breaks or discontinuities in their plotted peaks.
Analysis of Gaging-Station Records 75
fined, and therefore, that the regional skew is equal to regional pattern to the variation of skew among sites.the mean value of zero for the sample with an associ- The model for regional site-to-site variation of skew isated error equal to the sample variance of 0.31. That a regional mean value plus a random component thatis, the logarithms of peak discharges at individual sites is uncorrelated with any definable site characteristic,do have skewed distributions, but there is no definable Alternative hypothesis A was that regional relations
49° ~__ 120° ,124° y ~~T---- r -- 116°<^Vv nI
CANADA 100°
0 100 MILES
0 100 KILOMETERS
29°
GULF OF \
MEXICO
EXPLANATION
STUDY AREA
MAJOR BASIN DIVIDE
GAGING STATION
Figure 56. Gaging stations with sharp breaks or discontinuities in their plotted peaks.
76 Methods for Estimsting Magnitude and Frequency of Floods in the Southwestern United States
o o 111CO
cc 1110.I-LU LU LL
O
CO
100,000
10,000
1,000
100
10
09415560 WHITE RIVER TRIBUTARY
NEAR SUNNYSIDE, NEVADA
DRAINAGE AREA = 20.0 SQUARE MILES
MEAN BASIN ELEVATION = 6,240 FEET
YEARS OF RECORD = 15
YEARS OF NO FLOW = 5
10249850 PALMETTO WASH
TRIBUTARY NEAR LIDA, NEVADA
DRAINAGE AREA = 4.73 SQUARE MILES
MEAN BASIN ELEVATION = 7,440 FEET
YEARS OF RECORD = 14
YEARS OF NO FLOW = 1
0 100,000
LU C3 CC <I O CO
LU 0.
10,000
1,000
100
10
10247860 PENOYER VALLEY TRIBUTARY NEAR TEMPIUTE, NEVADA
DRAINAGE AREA = 1.48 SQUARE MILES
MEAN BASIN ELEVATION = 5,680 FEET
YEARS OF RECORD = 18
YEARS OF NO FLOW = 8
10172902 DEAD CEDAR WASH NEAR WENDOVER, UTAH
DRAINAGE AREA = 5.00 - SQUARE MILES
MEAN BASIN ELEVATION = 6,910 FEET
YEARS OF RECORD = 18
. YEARS OF NO FLOW = 8
80 70 50 30 20 10 5 21 80 70 50 30 20
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
10 2 1
EXPLANATION
LOG-PEARSON TYPE III FITTED RELATION Interagency Advisory Committee on Water Data (1982)
REGIONAL RELATION FOR NORTHERN GREAT BASIN REGION (6)
Figure 57. Examples of plotted peaks for gaging stations with samples that are inadequate to define a flood-frequency relation.
Analysis of Gaging-Ststion Records 77
of skew coefficient can be defined. Alternative hypothesis B was that the gaging-station records fit the log-normal distribution, and therefore, station and regional skew equal zero.
Data and methods. A sample of 1,061 gaging- station records was used to estimate relations of
regional skew coefficient for the study area. A station skew coefficient was computed for the loga rithms of the series of annual peak discharges at each gaged site. A skew computed from a sample by the method of moments is a biased estimate of the population skew; therefore, the computed skew
c>1
I1(~~1
49°' r _ 12 / "1-Vv
/
"-^Asni
0°~~~" rf
J^-JiN GT ON- ~\
~T
t
/1
1
116°-]- - r -
/
\\
C A112°
-- T -_.
N A D A 108°
- T -- r - T --104°
... .j
i1
1
"" 1"
NORTH
DAKOTA
100°
45'
0 100 MILESKvV^0 100 KILOMETERS
MEXICO
EXPLANATION
:|li" ;;1 STUDY AREA
MAJOR BASIN DIVIDE
+ GAGING STATION
Figure 58. Gaging stations with samples that are inadequate to define a flood-frequency relation.
78 Methods for Estimating Magnitude and Fraquancy of Floods in tha Southwestarn United Statas
Table 25. Percentage of gaging stations with undefined flood-frequency relations compared with basin and climatic characteristics in the southwestern United States
[ANOVA, analysis of variance significance level. The gaging stations were coded with a 1 if the attribute is present and a 0 if the attribute is not present. The mean of the I's and O's in each class of basin or climatic characteristic is the percentage of the attributes in each class. An ANOVA was performed on the three classes to test if there is a significant difference in means (percentages) between the three groups (three classes of basin or climatic characteristic)]
Class
Percent age of sta tions with
frequency relations
ANOVA signifi cance level
Drainage area, in square miles
Less than 50 50 to 200 More than 200
756293274
2997
<0.01
Latitude, in degrees
Less than 3737 to 41More than 4 1
559482282
2716 <.0113
Mean basin elevation, in feet
Less than 6,000 6,000 to 8,000 More than 8,000
408471381
3019
5.01
Mean annual precipitation, in inches
Less than 16 16 to 25 More than 25
535442266
3385
Mean annual evaporation, in inches
Less than 40 40 to 55 More than 55
421541361
92132
was multiplied by a correction factor of l+(6/AO, in which N is sample size, to obtain a nearly unbiased estimate (Tasker and Stedinger, 1986). The adjusted skew coefficient was used for all sites.
A cumulative distribution plot of the skew coef ficients was a straight line on an arithmetic-normal scale, but the line had a sharp break at a skew of about 1.5. Nineteen sites with a skew greater than 1.5 were considered to represent a different popula tion and therefore were deleted from the regional
analysis. All the sites with skews greater than 1.5 had a peak discharge that is a high outlier in their individual sample; therefore, those 19 sites were considered to be contaminated by the high outliers. The final sample of 1,042 adjusted skew coeffi cients has a cumulative distribution that plots as a straight line and has a mean of 0.028, a median of 0.011, and a variance of 0.31. Thus, the distribution is considered normal with a mean of about zero.
Seven regional skew relations were tested in this analysis: one relation for the study hypothesis, five relations for hypothesis A, and one relation for hypothesis B.
1. Regional relations of skew coefficient cannot be defined. The regional skew is equal to the mean value of zero for the sample with an associated error equal to the sample variance of 0.31 (study hypothesis).
2. Spatial relations for hypothesis A were tested using a published geographic isoline map of skew coefficient (Interagency Advisory Com mittee on Water Data, 1982, plate 1).
3. Spatial relations for hypothesis A were tested by determining new geographic isoline maps of skew coefficient.
4. Spatial relations for hypothesis A were tested by dividing the study area into geographic regions of uniform skew coefficient.
5. Relations between skew coefficient and basin and climatic characteristics for hypothesis A were tested using multiple-regression analy sis.
6. Relations between skew coefficient and basin and climatic characteristics and geographic regions of uniform skew for hypothesis A were tested together using multiple- regression analysis.
7. Gaging-station records fit the log-normal distribution, and, therefore, regional and sta tion skew are equal to zero (hypothesis B).
The overall accuracy of the estimated regional skew relations was evaluated by comparing the computed mean-square error of each relation. A split-sample approach was used to estimate the mean-square error. The sample of gaged sites was split into 695 sites to develop the regional relations for estimating skew coefficient, and the relations were applied to the remaining 347 sites to estimate the mean-square error. The mean-square error is the variance of the difference between skew estimated from the regional relation and the at-site skew. The
Analysis of Gaging-Station Records 79
sites were listed numerically by station number and then assigned alternately to the first or second group. The procedure resulted in two samples with similar basin and climatic characteristics.
Another method used to evaluate the accuracy of the different regional skew relations was to apply the estimated regional skews to predictions of regional 100-year peak discharges. For the regional relations with a station skew coefficient, 100-year peak discharges were computed for each station using skew coefficients weighted by the associated errors of the station skew and each regional skew (Interagency Advisory Committee on Water Data, 1982, p. 10-14). For the relation of a log-normal distribution, 100-year peak discharges were com puted by fitting the log-normal distribution to the station records. Regional regression relations were then developed for the 100-year peak discharge for each regional skew. To reduce the large variation in flood characteristics for the study area and to pro vide a more homogeneous sample for a comparison of regional skews, the study area was divided into 23 regions with similar flood characteristics. Regional regression equations were developed for those 23 regions, which were preliminary and are not the final flood regions used in the report. The 23 regions were delineated during the procedure to estimate geographic regions of uniform skew. All
the regression relations used for comparison among the different regional skew relations had the same explanatory variables.
Application of the relations for regional skew to the estimation of regional 100-year peak discharges was evaluated by comparing a weighted average standard error of estimate of the regression rela tions. The weighted average standard error of estimate is the average standard error of estimate for the 23 regions weighted by the number of gaged sites in each region.
Study hypothesis. The study hypothesis is that regional relations of skew coefficient cannot be defined, and, therefore, the regional skew is equal to the mean value of zero for the sample. For a comparison with the other regional skew relations, the sample variance of 0.31 can be considered analogous to a mean-square error. The application of the regional skew to a regression of 100-year peak discharge in 23 regions resulted in a weighted average standard error of estimate of 0.29 log units.
Published isoline map. The Interagency Advi sory Committee on Water Data (1982, plate I) developed an isoline map using peak-discharge records from about 3,000 gaging stations through out the United States. The isoline map has an overall mean-square error of 0.30, which is similar to the mean-square error computed for the other
oI- >
9,000
Huj 8,000 -
in in
7,000 -
m 6,000 -
5,000 -
4,00028
I30 32 34 36 38
LATITUDE, IN DEGREES
I 40
I 42
_1_ 44 46
Figure 59. Elevation zone for mixed population of floods caused by thunderstorms and snowmelt in the southwestern United States.
80 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
Table 26. Summary of analyses of mixed-population flood records for the southwestern United States
Station number
072040000720450007206400072085000825250008268500082756000827900008284300082845000837850008381000091464000917750009182000091840000921660009224820092252000927800009288000092881500928850009307500093085000931300009318000093245000932650009330500093370000933850009340000093425000934400009363000093635000936550009366500093840000940445010023000101460001014820010148500101655001017270010210000102164001024140013083000
Drain age area, in aquare
miles
73.856.0
7.465.025.165.637.0
305.045.0
193.0189.087.014.112.07.6
74.97.93.66.6
15.7140.056.1
950.0297.032.0
415.0190.0208.0138.0105.068.1
1.986.9
298.069.897.4
1,09037.0
331.0747.0
69.252.295.619.4
490.09.8
25.016.459.415.853.7
Site elevation, in
feet
8,1978,1957,8606,7209,4296,6707,2235,8597,1896,9457,5036,6758,4008,1207,0704,2406,3006,2006,2007,8606,6706,7905,5126,0007,1906,0006,2106,0506,2106,4006,4008,6007,5987,0527,9417,3025,9608,1055,9756,0105,9006,4105,2806,1205,0275,3206,2006,7606,0006,7404,820
100-year peak discharge, in cubic feat
Rainfall
301650240
3,0601,1401,290
5903,7104,8203,8903,0707,100
34988247
12,0001,020
763839200
1,0003,5302,8102,4501,8309,5702,9205,6204,3703,5201,700
9572,250
15,7001,4603,440
13,3001,8506,620
12,1001,610
4441,010
9901,250
6851,5002,6602,1201,150
210
Snowmelt
234650
651,260
308706447
2,4002,3004,7502,3901,750
16081137
1,20013536
325240
1,020988
3,720500
1,2902,6101,7002,7602,0502,430
493267
2,3407,2801,3602,370
15,1001,4302,1404,090
895221754126
1,600365470436993286141
Com posite
320760240
3,3001,1401,290
6803,7104,8205,5003,4007,100
3491,060
5112,000
1,020763860250
1,2503,5303,9002,4502,2209,7002,9205,6204,3704,1001,700
9572,650
15,7001,5003,440
15,8001,9406,620
12,1001,800
4441,1201,0001,700
6851,5002,6602,1201,150
245
per second
Annual maximum
298741186
3,0001,0701,250
5723,7404,5005,4503,4006,070
295959
5112,500
982770865250
1,3203,1703,8502,4102,4109,3302,6204,8603,9204,1101,790
7742,620
15,6001,6503,340
15,7001,8005,900
10,7001,490
3521,0901,0201,730
570870
2,1601,7401,240
241
Ratio of composite to
annual maximum
1.071.031.291.101.071.031.19.99
1.071.011.001.171.181.111.00.96
1.04.99.99
1.00.95
1.111.011.02.92
1.041.111.161.111.00.95
1.241.011.01.91
1.031.011.081.121.131.211.261.03.98.98
1.201.721.231.22.93
1.02
Analyais of Gaging-Station Records 81
methods used in this analysis. The application of Isoline maps. An isoline map of skew coeffi-regional skews obtained from the isoline map to a cient was developed using a kriging procedureregression of 100-year peak discharge in 23 regions where the study area was divided into a uniformresulted in a weighted average standard error of grid of 33 rows and 33 columns. Thus, the squareestimate of 0.29 log units. cells are about one-half degree on a side. The mag-
,.124'
( ^
49°/ r -_ 120°Si '-I----.
CANADA 100°
P" "- -r - » - *- - - --
OR ADO ', KANSAS
0 100 MILES
0 100 KILOMETERS
MEXICO
EXPLANATION
STUDY AREA
MAJOR BASIN DIVIDE
GAGING STATION
Figure 60. Gaging stations with an analysis for a mixed population of floods caused by thunderstorms and snowmelt.
82 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
nitude of estimated isolines ranged from -0.4 to 0.3, with an estimated mean skew of zero. The kriged map had a mean-square error of 0.31, and application of the kriged isoline regional skew to a regression of 100-year peak discharge in 23 regions resulted in a weighted average standard error of estimate of 0.29 log units.
An isoline map also was developed using a geographic-information system procedure. No grid was used, and the isolines were estimated from the irregularly spaced gaged-site locations using a two- variable five-step interpolation method. The magnitude of the estimated isolines ranged from -0.6 to 0.5 with an estimated mean skew of zero. The mean-square error from that map is 0.29 log units.
Geographic regions of uniform skew coeffi cient. The optimum number of geographic regions with a uniform skew coefficient was determined using the following procedure. Twenty-five regions were first delineated using boundaries of drainage- basin divides and large rivers. The regions were selected on the basis of similar flood characteristics and potentially similar skew coefficients. The sec ond step was to examine the uniformity of skew coefficient within each region. Skew coefficient was plotted against latitude and longitude, and the magnitudes and areal trends in skew coefficient
were compared with adjacent regions. Several region boundaries were moved to ensure uniformity of skew coefficient within each region. These initial adjustments resulted in a reduction in the number of regions to 22.
Statistical tests were used to evaluate if the populations of skew coefficient in adjacent regions were significantly different. The mean was used as the primary measure of central tendency of skew coefficient for a region because the majority of regions have a normal distribution of skew coeffi cient. Thus, a Mest was the primary test used to evaluate the difference between means of regions. A nonparametric Mann-Whitney test was a second ary test used to evaluate the difference between medians of regions.
The two statistical tests were performed on all adjacent regions, and in all comparisons the Mann- Whitney test gave the same results as the r-test. If two adjacent regions did not have significantly different skew coefficients, the regions were com bined. During consolidation of the regions, the new combined regions were tested against adjacent regions each time a new combined region was made. The final number of significantly different regions was nine, and the range in values of mean skew coefficient was -0.22 to 0.18.
1,000
o oLU C/3
ccLU 0.
occ
o z
LU C3 CC
I O C/3
LU 0.
100
10
RAINFALL
-- SNOWMELT
- COMPOSITE
ANNUAL MAXIMUM
50 20 10 5 21
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
0.2
Figure 61. Flood-frequency relations for South Fork of Rock Creek near Hanna, Utah (09278000).
Analysis of Gaging-Station Records 83
Regression analysis was used as a further test of significance of the regions and to estimate the mean-square errors of the uniform-region method. The nine regions were grouped into four regions of uniform skew for the regression analysis. The nine regions are needed for a geographical representation because some areas of similar skew coefficient are separated by an area of different skew coefficient and could not be combined in the two-dimensional space. The mean skew coefficients of the four regions are -0.20, -0.062, 0.078, and 0.17.
Three dummy variables were used to represent the four regions in the regression analysis. The vari ables were coded as follows:
Regioi
ABCD
n RA
1000
Variable
RB
0100
RC
0010
The three dummy variables and regression con stant are all significant at better than the 0.05 level. The regression equation representing the four regions has an R2 value of 5.2 percent and a mean-
square error of 0.32. Thus, the four regions only explain 5.2 percent of the variation in skew coeffi cient, and the mean-square error is about the same as the variance of the sample of 1,042 gaged sites, which is 0.31. The application of the four regions of uniform skew to a regression of 100-year peak discharge in 23 regions resulted in a weighted aver age standard error of estimate of 0.29 log units.
Relation between skew coefficient and basin and climatic characteristics. Multiple-regression analysis was used to investigate the relation between skew coefficient and basin and climatic characteristics. Investigated characteristics were drainage area, in square miles; stream length, in miles; main channel slope, in feet per mile; mean basin elevation, in feet; site elevation, in feet; mean annual precipitation, in inches; precipitation inten sity for 24 hours and 100-year recurrence interval (I24_100), in inches; and mean minimum January temperature, in degrees Fahrenheit.
The regression analysis used both log- transformed and untransformed independent vari ables, and generally the log-transformed values had more significant relations. Several combinations of the log of mean annual precipitation, mean basin elevation, and I24_100 are significant at better than
1,000
a z OoHI 03
£E HIa. l-Hl HI H.
O
CO
HI CD CC <I O 03
HI D_
100
10
RAINFALL
..... SNOWMELT
COMPOSITE
ANNUAL MAXIMUM
90 80 50 20 10 0.2
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
Figure 62. Flood-frequency relations for Big Creek near Randolph, Utah (10023000).
84 Methods for Estimating Magnitude end Frequency of Floods in the Southwestern United Stetes
the 0.05 level. The largest R- value of combinations of those variables, however, is 3 percent. Thus, only 3 percent of the variation in skew coefficient can be explained by the investigated explanatory variables. The smallest mean-square error from the regression models is 0.31, which is the same value as the vari ance of the sample of 1,042 gaged sites. The application of the best skew-prediction equation of regional skew to a regression of 100-year peak dis charge in 23 regions resulted in a weighted average standard error of estimate of 0.29 log units.
Relation between skew coefficient and basin and climatic characteristics and uniform regions. Multiple-regression analysis was used to investigate the relations between skew coefficient, basin and climatic characteristics, and the four regions of uni form skew. The model for this evaluation was to log-transform all independent variables and to use the three dummy variables to represent the four regions of uniform skew.
The four uniform regions formed the best three- variable model with an R2 of 5.2 percent and a mean-square error of 0.32. Adding drainage area, 24-hour precipitation intensity for 100-year recur rence interval, and stream length to the equation increases the R2 to 6.6 and reduces the mean-square
error to 0.30. Thus, the six-variable model is a small improvement over the three-variable model, but none of the models explain a sufficient portion of the variation in skew coefficient to be accurate or reliable.
Log-normal distribution. This hypothesis is that the gaging-station records fit the log-normal distribution, and therefore, station and regional skew equal zero. Comparison to the other regional skew relations cannot be made using mean-square error because no prediction of skew is made. Also, this relation has no station skew and thus no vari ance of skews. One comparison can be made and that is by using the 100-year peak discharges com puted from fitting the log-normal distribution to the records at each site and applying the regional regression relations for the 23 regions. This applica tion resulted in a weighted average standard error of estimate of 0.29 log units.
Discussion. The analysis of regional skew coefficient failed to reject the study hypothesis. The study hypothesis was that regional relations of skew coefficient cannot be defined and thus the regional skew is equal to the mean value of zero for the sample with an associated error equal to the sample variance of 0.31. Five methods were used to
100,000
o o111 CO
Ill 111LJ_
OCO
o
111 C3cr
oCO
Q
^
111 CL
10,000
1,000
100
10
RAINFALL
..... SNOWMELT
COMPOSITE
ANNUAL MAXIMUM
50 20 10 5 21
ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT
0.2
Figure 63. Flood-frequency relations for Mill Creek near Moab, Utah (09184000).
Analysis of Gaging-Station Records 85
predict regional skew and to test hypothesis A that regional relations of skew can be defined. The five methods are a published isoline map, new isoline maps, geographic regions of uniform skew, relation between skew and basin and climatic characteris tics, and relation between skew and basin and climatic characteristics and geographic regions of uniform skew. These methods have mean-square errors of between 0.30 and 0.32; therefore, they all failed to improve on the mean skew of zero for the sample. The second test of applying the predicted regional skews to a regional regression of 100-year peak discharge also showed that the prediction methods offer no improvement in accuracy com pared with using a mean regional skew of zero. The weighted average standard errors of estimate from the regression analyses were 0.29 log units for the study hypothesis and all the predicted regional skews.
Results of the analyses support the study hypothesis that the regional skew is zero for the study area. The methods and results, however, did not provide conclusive evidence that hypothesis B is more or less accurate than the study hypothesis. Hypothesis B is that the gaging-station records fit the log-normal distribution, and, therefore, station and regional skew equal zero. Application of hypothesis B to prediction of regional 100-year peak discharges had the same average accuracy (weighted average standard error of estimate of 0.29) as the other regional skews. This similarity in accuracy does provide some evidence that many of the sites in the study area may have a log-normal distribution of annual peak discharges. However, classification of all sites as having a log-normal distribution cannot be made because many sites with long records have a clearly skewed distribution of the peaks plotted on log-normal probability paper. Characteristics of basin soils, storage capac ity of the basin, stream-channel size, and flood-plain width may cause a skewed distribution by having different effects on peak discharge, depending on the magnitude and frequency of the discharge. In addition, some samples of mixed populations of floods also may cause a skewed distribution.
The regional skew coefficient used in this study was zero with an associated mean-square error equal to the sample variance of 0.31. The weighted skew coefficients for station flood- frequency relations computed with this regional skew thus allow individual variations in skew
according to the mean-square error of the station record and the regional skew. Although this study did not prove that the log-normal distribution is applicable to many sites in the southwestern United States, the study results do justify further investiga tion of this hypothesis.
Summary of Analyses
Flood-frequency analyses were made of records at 1,323 gaging stations. The reliability of station flood-frequency relations was assessed by visual examination of how well the computed relations fit the plotted peak discharges, the presence or absence of outliers, and the shape exhibited by the plotted peaks. This examination resulted in defining flood-frequency relations at 1,059 gaged sites. The remaining 264 undefined sites were classified as having unreliable relations because of extremely poor fits of the computed relations to the peak- discharge data. The sites may have inadequate samples to define a relation or a non-LPIII distribu tion.
Sites with defined flood-frequency relations were classified as having plots of data that exhibit certain characteristics (table 23). Some sites have more than one characteristic. The expected smooth shape of an LPIII distribution was found at 38 percent of the sites. At 48 percent of the sites, a low-discharge threshold was used to truncate peaks identified as low outliers and a conditional- probability adjustment was used to compute the flood-frequency relation. High outliers were identi fied at 17 percent of the sites. Historical periods were used to extend the period of record at 12 per cent of all sites. A jump or dogleg in the plotted peaks was identified at 16 percent of the sites, and no adjustments were made to the frequency rela tions for these departures from the expected smooth shape.
The percentage of sites with plots of data that departed from the expected smooth shape was compared with incremental classes of some basin and climatic characteristics (table 24). Generally, the departures were not related to basin and climatic characteristics of the gaged sites. The few significant relations were that (1) low-discharge thresholds increased in more arid areas, (2) doglegs increased as drainage area increased, and (3) jumps decreased as mean annual precipitation increased.
86 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
An analysis was made of the mixed population of annual peaks caused by snowmelt and summer thunderstorms. A small sample of 51 gaging-station records was selected at sites expected to have a potential difference in flood-frequency relations computed from the mixed population and computed by separating the peaks, computing separate rela tions, and combining the relations into a composite relation. The average ratio of composite 100-year peak-discharge relation to mixed relation for the 51 sites was 1.08. That difference is considered small because of all the uncertainties inherent in flood-frequency analysis. Thus, the flood-frequency relations computed from the mixed populations apparently are adequate and no adjustments were made for this condition.
An analysis of regional skew coefficient was made for the study area. The methods of attempting to define a regional skew by spatial variation or by regression with basin and climatic characteristics all failed to improve on a uniform value of zero for the study area. The regional skew used in the study, therefore, was a value of zero, which was the mean of all the station skews analyzed with an associated error equal to the sample variance of 0.31 log units.
REGIONAL ANALYSIS
Multiple-regression analysis was used to relate flood-frequency relations that could be determined at gaged sites to basin and climatic characteristics. Ordinary least-squares (OLS) and generalized least- squares (GLS) regression analyses were used. A hybrid analysis (Hjalmarson and Thomas, 1992) of the station-year method and multiple regression developed during this study also was applied and used for areas where the standard multiple- regression method was judged to be inadequate. The final regional flood-frequency relations were defined for 12 regions (Regions 1-5, 7-9, 12-15) using GLS regression and for four regions (Regions 6, 10, 11, 16) using hybrid analysis. All 12 regions with GLS relations had less than 20 percent of their gaging stations with undefined flood-frequency re lations, and all 4 regions with hybrid relations had more than 30 percent undefined station relations. Results of these analyses are the regional equations for estimating flood-frequency relations at ungaged sites (tables 5-20).
Multiple Regression
The multiple-regression analysis consisted of an investigation of geographic variation of flood magnitudes, different forms of models, and the significance of available explanatory variables. The geographic variation of flood characteristics is not linear or consistent. Incorporation of geographic variables into the regression equations, therefore, is not practical, and the study area was divided into geographic regions of similar flood characteristics. The objective was to obtain the smallest number of geographic regions with predictive equations that are accurate, physically reasonable, and efficient for the user.
OLS and GLS regression analyses were used in this study. OLS analysis was used for prelimi nary analyses of delineation of flood regions, investigation of models, and selection of signifi cant explanatory variables. GLS analysis was used for refinement and to compute the final regression models.
GLS regression is considered to be a more appropriate method for developing regional regres sion models of streamflow characteristics than is OLS regression (Stedinger and Tasker, 1985). Regional regression models of streamflow charac teristics, such as flood-frequency relations, are commonly developed by regressing gaged-site flood-frequency relations on basin and climatic characteristics. Using flood-frequency relations at gaged sites as a response variable may violate two assumptions of OLS regression. Those assumptions are (1) that the response variable at each site is independent and (2) that it has equal variance. Peak discharges for nearby watersheds may be correlated as a result of similar climatic events. Streamflow records have different lengths and at-site variability, and therefore the computed flood-frequency rela tions have unequal variances. GLS takes into account the possible cross correlation and unequal variance of flood-frequency estimates at gaged sites.
Models Investigated
Several model forms were investigated. The objective was to find the model form that has the best fit for the relations of flood characteristics compared with basin and climatic characteristics. The model should be intrinsically linear in order to
Regional Analysis 87
perform standard linear-regression techniques. Many previous studies have shown that the multiplicative model (all variables are log-transformed) is appli cable to regional flood-frequency studies. When the response and explanatory variables are log- transformed, the resulting model commonly is lin ear. That model was used as the base method, and other models were investigated and evaluated. Poly nomial models were tested, dummy variables were used, and various transformations of the explanatory and response variables such as recipro cals, interaction terms, and fractional exponents (Draper and Smith, 1981, p. 218-225) were tested.
Explanatory Variables Investigated
Nineteen explanatory variables were investi gated as possible predictors of T-year discharges. The following list shows the variables, units of measurement, and number of sites with the variable measured:
1. Drainage area, in square miles (1,059);2. Main channel slope, in feet per mile (1,027);3. Main channel length, in miles (1,018);4. Mean basin elevation, in feet above sea level
(1,031);5. Elevation of gage datum, in feet above sea
level (963);6. Forested area, in percent (1,010);7. Latitude of gaged site, in decimal degrees
(1,059);8. Longitude of gaged site, in decimal degrees
(1,059);9. Mean annual precipitation, in inches (1,020);
10. 100-year 24-hour maximum precipitation, in inches (1,043);
11. Mean annual free water-surface evaporation, in inches (1,054);
12. Distance from major moisture source, Gulf of Mexico, in hundreds of miles (1,059);
13. Distance from major moisture source, Gulf of California, in hundreds of miles (1,059);
14. Relation of gaged site to major orographic barriers, attribute dimensionless (1,059);
15. Basin shape, length squared divided by drain age area, dimensionless (1,018);
16. Potential vegetation at gaged site, in discrete units (1,059);
17. Field-measured channel geometry, active channel width, in feet (59);
18. Channel slope of lower one-third stream length, in feet per mile (142);
19. Isoerodent factor, dimensionless (220).Variables 1-8, 15, and 18 were determined
from the largest scale topographic maps available. Mean annual precipitation was determined from maps of mean annual precipitation for each State published by several different sources (see p. 16). The distance from major moisture sources was de termined by measuring the distance from gaged sites to points selected near the Texas coast for the Gulf of Mexico (28° latitude, 97° longitude) and in the northern part of the Gulf of California (29° lati tude, 113° longitude). The 100-year 24-hour maximum precipitation (Miller and others, 1973a- i), mean annual free water-surface evaporation (Farnsworth and others, 1982), and relation to oro graphic barriers were determined at gaged sites using geographic-information-systems techniques.
The relation of gaged site to major orographic barriers was determined in several steps. First, the major orographic barriers were selected and outlined on a map of the study area. Such barriers include the Sierra-Cascade Mountains of eastern California and the mountains of central Arizona. Windward and leeward sides of the barriers were delineated on the basis of dominant directions of moisture or storm movement. The sites on the windward side were assigned positive numbers, and sites on the leeward side were assigned negative numbers. A scale of -3 to +3 was used. The largest numbers were assigned to the highest and most con tinuous barriers. The angle of moisture movement also was factored in; right angles received larger num bers and obtuse angles received smaller numbers.
A map of potential natural vegetation (Kuchler, 1964) was examined for possible use as an explana tory variable in the study area. The locations of the 1,059 gaged sites were plotted on the map. The types of vegetation were grouped into two major classes: (1) forests and dense shrubs and (2) shrubs and grasslands. Differences of the standardized val ues of the 100-year peak discharge (<2 10Q/AREA0 ') for the two general vegetation types at the gaging stations were examined visually and using statistical tests of subsamples.
A partial sample of 59 field measurements of channel geometry was obtained from Hedman and Osterkamp (1982). The channel slope of the lower one-third stream length was measured from the
88 Methods for Estimsting Magnitude snd Frequency of Floods in the Southwestern United States
largest scale topographic map available for 26 gaged sites with drainage areas ranging from 0.5 to 1,700 mi2 in southern Arizona. The same variable was measured for an additional 116 sites with a drainage area of greater than 200 mi2 throughout the study area. An isoerodent factor (Fletcher and others, 1977) was determined for 220 gaged sites in New Mexico using a geographic-information- systems technique.
Results
Flood regions. A single regression equation for the entire study area does not adequately explain the variation in flood characteristics. The OLS stan dard errors of estimate for 7-year discharges were more than 100 percent for all attempted single mod els. In addition, except for a high-elevation region, a single relation for a stratum of an explanatory variable was not found. The study area, therefore, was divided into 16 flood regions, and separate regression equations were developed for each region. Use of the 16 flood regions removes some of the variation in the system not explained by available explanatory variables and thus makes the subsequent equations simpler. The flood regions were delineated on the basis of general magnitudes of floods, the meteorologic cause of floods (snow- melt, summer thunderstorms, or cyclonic rainfall), elevation of the sites, and geographic patterns in residuals from the regression analysis. No obvious, consistent geographic patterns in residuals were found; therefore, an explanatory variable could not be developed that could explain the study-wide geo graphic variation. Geographic clusters of residuals from study-wide regressions were used to help delineate boundaries of the regions.
The first stratification was into High-Elevation Region 1, which occurs throughout the entire study area. Sixteen percent of the gaged sites were placed in this region. A regression of 100-year peak dis charge on drainage area was made for all sites in the study area, and 90 percent of the residuals for the high-elevation sites were negative. High- Elevation Region 1 is dominated by floods caused by snowmelt (table 4). Thunderstorms occur in this region, although large floods caused by thun derstorms are rare. The lower boundary of the high-elevation region coincides with the estimated elevation threshold for large floods caused by thun derstorms (fig. 5). To determine if a study site fits
in this region, the elevation of the study site is used not the mean basin elevation. The elevation threshold remains constant at 7,500 ft for all sites south of 41° latitude, and the threshold decreases north of that latitude. North of 41° latitude, the threshold is approximately a flat plane that slopes about 300 ft for each increment of 1 ° of latitude.
The second stratification of data was into 1 5 geographic low- to middle-elevation flood regions where the elevations of the gaged sites are below the boundary of High-Elevation Region 1. The boundaries of these regions are based mainly on drainage divides.
Models. The model that best describes most regional flood-frequency relations for this study is the multiplicative model (equations 3A, 35), where all variables are log-transformed. The most signifi cant explanatory variable is drainage area, and in most flood regions the log of drainage area is lin early related to the log of the 7- year discharge. In two flood regions (Regions 12 and 13), however, a plot of log T-year peak discharge and log of drain age area indicates a slightly curvilinear relation. Eychaner (1984) found this relation for a region in southern Arizona and fit the data using a second- order polynomial described by the following equation:
logQT = a
where
, (9)
QT = peak discharge, in cubic feet persecond, for 7-year recurrence inter val;
AREA = drainage area, in square miles; and a, fej, and &2 = regression coefficients.
This model fits the two regions with curvilinear relations in this study. Tasker and others (1986), however, used a transformation other than logs to account for the nonlinearity for the same data as Eychaner (1984). The transformation consisted of raising drainage area to a negative fractional power. The equation used in Tasker and others (1986, p. 112) is shown as equation 4B in this report and is repeated here for just one explanatory variable:
\ogQT =a
The model suggested by Tasker and others (1986) was used in this study to fit the nonlinear
Regional Analysis 89
relations for 7-year discharge and drainage area in the two flood regions. The equations were fit by iteratively selecting an exponent for drainage area, performing a regression analysis with log-transfor mations for all other variables, and comparing the standard error of estimate and plotting until the plot appeared linear. Illustrations of the two models and how they fit the data in the Southern Arizona Region 13 are shown in figures 64 (equation 9) and 65 (equation 4B).
A third model (equations 5A, 5B) was used in the Southeast Region 16. In Southeast Region 16, drainage area and mean annual evaporation are sig nificant explanatory variables using equation 3A. The plot of log QT and logAREA appears linear. A plot of the residuals from that relation and the log of mean annual evaporation, however, exhibits a slight curvilinear relation with more curvature and smaller residuals for large values of mean annual evaporation. In addition, the sample of gaged sites in the region has few sites with small drainage areas and large values of mean annual evaporation. To account for the apparent curvilinear relation of the residual from the QT and drainage-area relation and the poor definition of the relation for small drainage areas with large mean annual evaporation, equation 5B was fit to the data:
\ogQT = logo + MogAREA + clog(EVAP-d).
This relation has the best fit for larger values of AREA and smaller values of EVAP. For large val ues of EVAP, the relation is an average of the relation between logQT and logAREA and the non linear relation between \ogQT and logAREA and logEVAP. Averaging where EVAP is large pro duced the most reliable overall relation; the distribution of residuals about the relation is more random in appearance and homoscedastic.
Significance of explanatory variables. The explanatory variables used in the predictive equations for the 16 flood regions are drainage area, mean basin elevation, mean annual precipitation, mean annual evaporation, latitude, and longitude. In the study area, the ranges for these variables are drainage area, 0.01 to 1,990 mi2 ; mean basin elevation, 350 to 12,000 ft; mean annual precipitation, 2 to 68 in.; mean annual evaporation, 29 to 100 in.; latitude, 29 to 45°; and longitude, 100 to 121°. The range of values for explanatory variables in each of the 16 flood regions
is shown in the plots of explanatory variables used in the 16 sets of regional flood-frequency relations. The figure numbers of these plots are referenced in column 6 of table 4. The range of values in a region can be large or quite small depending on the avail able data. For example, the range of drainage area for gaging stations in Region 7 is about 6 to 350 mi2 , and the range of drainage area in Region 12 is about 0.1 to 1,500 mi2 .
All the explanatory variables investigated in this study except potential vegetation were significantly related to 7-year discharge in regressions for the entire study area. Only six variables were used in the regional regression equations because either the other variables were correlated to those six vari ables or the other variables were not significant in the reduced variability within the 16 individual flood regions.
The explanatory variables that were measured for at least 90 percent of the gaged sites were inves tigated as possible predictors of 7-year discharges in all 16 flood regions. These 15 variables are num bered 1 to 15 on page 88. Routines, such as all possible regressions and stepwise regressions, were used to select the best possible models for each region. Drainage area was always the most signifi cant variable and the first variable selected in all models. Multiple-variable models were used only if the second or third variable reduced the standard error of prediction by at least 5 percent and the coefficients of the additional variables were reasonable (that is, the sign and magnitude matched the conceptual model of flood characteristics).
Potential natural vegetation (Kuchler, 1964) was not included in the regression analysis because an initial investigation showed it had no significant relation to flood characteristics. The variable was examined by plotting the gaged-site locations on a map of the study area and grouping the vegetation into two major classes. Differences of the standard ized values of the 100-year peak discharge (2io(/ AREA0 - 5 ) for the two general vegetation types at the gaging stations were examined visually and using statistical tests of subsamples. The coefficient of variation was nearly 1 for the standardized flood values, and no difference between the mean of the standardized flood values for the two general types of potential vegetation was detected at the 5-percent significance level (cc<0.05).
Potential natural vegetation at a gaged site as an explanatory variable has limited application for
90 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
regional flood-frequency analysis. For large basins, the vegetation at the gaged site may be much differ ent from the vegetation in the basin. Because the basin boundaries for the gaging stations have not been digitized, a comprehensive examination of vegetation as an explanatory variable was not made.
Three additional explanatory variables that were measured for only a small sample of the gaged sites were field-measured channel geometry, channel slope of lower one-third stream length, and the isoerodent factor (items 17-19, p. 88). A sample of 59 field measurements of channel geometry was obtained from a published report (Hedman and Osterkamp, 1982). Previous studies indicated that field measurements of channel geometry are effec tive predictors of flood characteristics (Wahl, 1984). Although field measurement of channel geometry is a valid method, it was rejected as an explanatory variable for this study. Regression analyses of the sample of gaged sites indicated that adding a channel-geometry variable to regression equations with basin characteristics did not signifi cantly improve the accuracy of the estimating equations. Other reasons for rejecting channel geometry are the requirement of field visits, the required field training, and a question of stationarity at some sites.
The channel slope of the lower one-third stream length was examined for 26 gaged sites with drain age areas ranging from 0.5 to 1,700 mi2 in southern Arizona and for an additional 116 sites with a drainage area of greater than 200 mi2 throughout the study area. Attenuation of peak discharge was previously estimated for streams in southern Ari zona by Eychaner (1984, p. 39), who recognized the difficulty of quantifying attenuation. The channel slope of the lower one-third stream length can be consistently measured, and this variable could be a measure of the lateral spreading and attenuation of peak discharge. A significant relation (a<0.05) between 7-year discharges and slope of the lower one-third of the stream channel was found for the sample of streams in southern Arizona («=26), where attenuation of peak discharges has been observed at many sites. The estimation of 7-year discharge, however, was not improved using the lower one-third slope variable for a sample of sites with large drainage areas (n=l 16) for much of the study area. The relation for the streams in southern Arizona may have been significant because of the influence of other factors, such as reduced tributary
inflow from distributary-flow areas that are com mon in southern Arizona. Because there was no improvement in regression relations for the sample of sites with large drainage basins, this variable was not determined for all the sites in the study area.
The isoerodent factor that was determined for 220 sites in New Mexico was a significant explana tory variable in a nationwide flood study by Fletcher and others (1977). That factor was rejected in this study because it is highly correlated with the T-year maximum precipitation intensity. The 100- year 24-hour maximum precipitation is considered a more reliable variable than the isoerodent factor. The 100-year 24-hour maximum precipitation factor was determined for all sites in the study area. In addition, the isoerodent factor is not an accurate indicator of flood characteristics in middle- to high- elevation areas. In middle- to high-elevation areas, the isoerodent factor increases as the magnitude of peak discharge decreases.
Regression relations. Study-wide relations of flood characteristics are discussed in this section. Two correlation matrices were computed for low- to middle-elevation sites and for high-elevation sites (table 27). The correlation matrices show the degree of correlation between all pairs of explanatory vari ables that were determined for more than 90 percent of the sites and between the 100-year peak dis charge and each of the explanatory variables. The coefficients reflect the degree of correlation between pairs of variables but do not take into account the fact that other variables can affect the simple two-way correlation.
Some important information contained in the correlation matrices is the degree of correlation between explanatory variables. Using highly corre lated variables in a regression relation can cause multicollinearity, which can cause unrealistic and unstable regression coefficients. Highly correlated explanatory variables (r>0.7), therefore, should not be used in the same regression equation. The selection of which correlated variable to use in a predictive equation in this study was based on the regression error associated with the variable and the relative ease of determining the particular variable.
To obtain a general picture of the relative importance of the explanatory variables in the study area, a stepwise regression was performed on all sites in the low- to middle-elevation group for the 10- and 100-year peak discharges (table 28). The stepwise regression was based on an F-statistic
Regional Analysis 91
criterion (F>4) in which each variable is added according to the largest partial correlation, and variables already in the equation can be removed (Minitab, 1988, p. 121-127). All variables shown in table 28 are significant at better than the 5- percent significance level. A stepwise regression also was developed for the high-elevation region, and drainage area and mean annual precipitation were the most significant variables for this region (table 5). For the 100-year peak discharge in the low- to middle-elevation regions, the most signifi cant explanatory variables in order of importance were drainage area, latitude, orographic influence, mean basin elevation, basin shape, precipitation intensity, mean annual precipitation, and distance from the Gulf of Mexico. The 10-year peak- discharge relation is similar to the 100-year relation in the significant variables and the order of importance of variables.
An example of two highly correlated variables is latitude and mean annual evaporation, where lati tude appears in the study-wide stepwise regression and mean annual evaporation appears in regional relations for two flood regions. The correlation coefficient between those variables is -0.82. In the flood regions where flood characteristics are more homogeneous and relations are more reliable, mean annual evaporation is a better predictor of T-year discharge than latitude.
The magnitude and signs of the coefficients of the explanatory variables in the study-wide relations provide some information about the study area (table 28). The coefficient or exponent for drainage area averages about 0.6. The coeffi cient for latitude is negative, which indicates that peak discharges decrease in magnitude in a north ward direction. Orographic influence is significant, and that influence is incorporated in the geographic boundaries of the 15 low- to middle-elevation flood regions. The coefficient for mean basin elevation is negative, which indicates that peak discharges decrease in magnitude as elevation increases. The coefficient for distance from the Gulf of Mexico is negative, which indicates decreased peak discharge with increased distance. Basin shape and precipita tion intensity (24-hour 100-year recurrence interval) coefficients have positive signs, which indicate increased discharge with increased magnitude of these variables.
Mean annual precipitation was one of the least significant variables in the 100-year discharge equa
tion for the entire low- to middle-elevation study area (table 28). The negative coefficient for mean annual precipitation does not agree with the posi tive coefficients determined for Regions 1 and 3 (tables 5, 7). This disagreement shows one of the limitations in attempting to define a single peak- discharge relation for a heterogeneous area such as the arid southwestern United States.
The flood regions have vastly different flood characteristics. Some similarities are apparent, how ever, when the regions are grouped into areas on the basis of latitude. The relations between 100-year peak discharge and drainage area were compared for three groups of regions (fig. 66). The northern regions (2-4) have an average regression constant of 61 and an average exponent for drainage area of 0.69. The middle regions (5-9, 15) have an average regression constant of 400 and an average exponent for drainage area of 0.45. The southern regions (10-14, 16) have an average regression constant of 970 and an average exponent for drainage area of 0.54.
The 100-year peak-discharge relations for the northern regions have a small variability among regions, small peak discharges for small drainage areas, and a generally steep slope of the relations (fig. 66). The relations for the middle regions have a large variability among regions, moderate magni tude peak discharges for small drainage areas, and a moderate slope of the relations. The magnitude of peak discharges estimated for large drainage areas is similar for the northern and middle regions. The relations for the southern regions have a moderate variability among regions, consistently large peak discharges for all size drainage areas, and a moder ate slope of the relations.
Stratification of the data into increments of explanatory variables was evaluated. The final flood regions and models are stratified by elev ation, where all sites above a specified elevation are placed into a single high-elevation flood region. The remaining low- to middle-elevation sites are placed into 15 geographic regions. A stratification based on drainage area was tested. In each flood region, sites were placed into two groups depending on whether drainage area was less than or greater than 50 mi2 . A multiple-regression analysis was performed on each group, and the results were com pared with the relations for nonstratified sites. The standard errors and regression coefficients for the unstratified and stratified samples were about the
92 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
same. There tended to be larger standard errors for the small drainage-area group and smaller standard errors for the large drainage-area group, but the differences in errors were small. Significant improvement in regression relations, however, was not made with the drainage-area stratification.
A total of 41 gaging stations were considered to have flood-frequency relations that were regional outliers in the regression analyses. The stations were deleted from the computation of the final GLS regression relations. The outliers are 5 percent of the total stations in the 12 flood regions for which GLS regression equations were derived. One region Western Colorado Region 9 had 14 percent, two regions had about 7 percent, and the remaining regions had less than 5 percent of the
stations deleted. The stations were deleted on the basis of visual examination of the plots of residuals. About two-thirds of the outliers were more than two standard deviations from the mean of the residuals.
Because of their extreme values in a sample, outliers can cause spurious correlations, mask legiti mate correlations, or add important information to the sample. Therefore, the change in regression relations caused by deleting outliers needs to be examined. The deletion of outliers in this study caused an average decrease of about 15 percent in the prediction errors for the 100-year peak-discharge equations a signifi cant improvement in accuracy. The deletion of outliers caused small changes in the regression exponent for drainage area. For the 100-year peak-discharge equa tions, the average change in the exponent for drainage
1,000,000
100,000 -
o oUJ CO<r LU
O03
LU O CC
<LU Q_
10,000 -
1,000 -
100 -
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 64. Relation between 100-year peak discharge and drainage area for Southern Arizona Region 13.
Regionel Analysis 93
area was about 6 percent. The deletion of outliers had a larger effect on the second variable in the 100-year peak-discharge equations, where the average change in exponent was about 20 percent. This change matched the conceptual model for that variable in all the re gions, and in 70 percent of the regions, the second explanatory variable became more significant when the outliers were deleted.
Many of the outlier stations have basin or stream-channel characteristics that are not defined by available explanatory variables and that do not fit the population of streams represented by the majority of the sample of stations. These character istics, such as basins with large areas of permeable
rocks or distributary flow or stream channels that cause a large quantity of floodflow attentuation, were described in the section entitled "Excluded Streams and Distributary-Flow Areas." The regional models used in this study may not apply to streams with such characteristics.
Accuracy and split-sample analysis. The accu racy of the GLS regression models was determined by the average standard error of prediction, which is a measure of how well regression models esti mate the response variable at the calibration sites (tables 5-20). The process of determining the best regression equation is often called calibration. Another method of assessing accuracy that was
o oUJc/)ccUJ Q_
LL
O
COIDO
UJo cc < I oc/) Q * <UJ 0.
cc <UJ
0.2 0.4 0.6 0.8 1.0
(DRAINAGE AREA, IN SQUARE MILES)'0 ' 12
1.2 1.4
Figure 65. Relation between logarithm of 100-year peak discharge and drainage area for Southern Arizona Region 13.
94 Methods for Estimating Magnitude snd Fraquency of Floods in the Southwestern United States
used in this study was to estimate the prediction error using a split-sample technique, which is a measure of how well regression models estimate the response variable at sites other than calibration sites.
When a split-sample analysis is used to estimate prediction error, the data are split into two parts; one part is used to calibrate a new predictive model, and the other part is used to evaluate or validate the new model's performance. The new calibrated model is applied to the validation data set to esti mate the average prediction error and to evaluate the significance of the explanatory variables. If the sample contains a wide range and even distribution of the explanatory variables and the new model is well calibrated, the explanatory variables that were significant in the original model will be significant in the split-sample analysis.
A split-sample analysis was made for the pre dictive equations for the 12 flood regions with GLS regional equations (table 29). For each region, the gaging-station records were divided into one group with two-thirds of the data used for calibration of a new model. The second group with the remaining one-third of the data was used for validation and estimation of prediction error. The stations were ordered by station number and assigned alternately to each group. This procedure resulted in the cali bration group and validation group having similar basin and climatic characteristics.
The new regression models developed for the split-sample analysis had coefficients that were very similar to the original models (tables 5-20). In a few of the new models, some of the explanatory variables were not significant at the 5-percent level; however, to estimate prediction error, all new models used the same explanatory variables as the original models.
Most split-sample prediction errors are larger than the corresponding GLS prediction errors. Split-sample prediction errors estimated for Regions 3, 5, 7, 9, 14, and 15 are questionable because of the small sample size: less than 15 stations had data for error estimation. For example, the average computed split-sample prediction error for the six recurrence-interval peak discharges is smaller than the average GLS prediction error in Regions 3 and 14. The average split-sample prediction error for the six regions with more than 20 stations for error estimation is about 8 percent larger than the average GLS prediction error.
In addition to the split-sample analysis, another method was used to assess the accuracy or validity of the regression relations of 100-year peak dis charges for the 16 flood regions. Design-probability theory (Riggs, 1968, p. 13) was used to compare the computed 100-year relations to the plotted maximum peak discharges of record (figs. 19, 21, 23, 25, 28, 30, 32, 34, 36, 37, 39, 41, 42, 44, 47, and 49). Using the average length of independent station records in a region, the percentage of stations that should not have a 100-year peak discharge can be estimated. For example, design probability indicates that for a num ber of independent 20-year records about 82 percent should not have a 100-year peak discharge. For all the flood regions, the number of annual maximum peak discharges that plotted below the relation for the 100-year flood closely agreed with the number expected from the design-probability method.
Hybrid Method
The hybrid method was developed as part of this study to define regional flood-frequency relations for Regions 6, 10, 11, and 16, where many of the station flood-frequency relations appear unreliable. Flood- frequency relations could not be determined for more than 30 percent of the gaging stations in those regions because there were too few years with flow or the plot of the series of annual peaks could not be reliably fit by a LPIII probability distribution. The plots of the annual series of peaks frequently do not appear to define a smooth curve, and no basis exists for using a LPIII distribution or any other three-parameter relation to estimate the flood-frequency characteristics at these stations.
The hybrid method combines all the records of annual peaks at all the gaging stations in a region as in the station-year approach (Fuller, 1914) to produce regional flood-frequency relations. The station-year method is based on the assumption that independent records of annual peak discharge from a region can be combined to form one long composite record if the peaks of the individual records can be reduced to a common base. In previous applications of a station-year approach (Carrigan, 1971; Wahl, 1982), annual flood records were reduced to a common base by dividing each peak from a particular record by the mean of that record. The standardized peaks are assumed to be from the same flood population
Regional Analysis 95
<o
en o a.
Tabl
e 27
. C
orre
latio
n m
atrix
with
100
-yea
r pe
ak d
isch
arge
and
exp
lana
tory
var
iabl
es f
or t
he s
outh
wes
tern
Uni
ted
Sta
tes
[Var
iabl
es:
All
vari
able
s ar
e lo
g-tr
ansf
orm
ed e
xcep
t O
RG
, w
hich
is
an i
nteg
er a
ttrib
ute
rang
ing
from
-3 t
o +3
. G
10o-
100
-yea
r pe
ak d
isch
arge
, in
cub
ic f
eet
per
seco
nd;
AR
EA
, dr
aina
ge a
rea,
in
squ
are
mile
s; S
LO
PE,
mai
n ch
anne
l sl
ope,
in
feet
per
mile
; E
LE
V,
mea
n ba
sin
elev
atio
n, i
n fe
et a
bove
sea
lev
el;
PRE
C,
mea
n an
nual
pre
cipi
tatio
n, i
n in
ches
; IN
T,
100-
year
24-
hour
m
axim
um p
reci
pita
tion,
in
inch
es;
OR
G,
an i
nteg
er a
ttrib
ute
repr
esen
ting
orog
raph
ic i
nflu
ence
, -3
to
+3;
SHA
PE,
leng
th s
quar
ed d
ivid
ed b
y ar
ea,
dim
ensi
onle
ss;
LO
NG
, lo
ngitu
de,
in
deci
mal
deg
rees
; FO
RS,
for
este
d ar
ea,
in p
erce
nt;
EV
AP,
mea
n an
nual
fre
e w
ater
-sur
face
eva
pora
tion,
in
inch
es;
LA
T,
latit
ude,
in
deci
mal
deg
rees
; D
GO
C,
dist
ance
fro
m G
ulf
of C
alif
orni
a,
in h
undr
eds
of m
iles;
DG
OM
, di
stan
ce f
rom
Gul
f of
Mex
ico,
in
hund
reds
of
mile
s; L
EN
G,
stre
am l
engt
h, i
n m
iles;
and
DA
TU
M,
site
ele
vatio
n, i
n fe
et a
bove
sea
lev
el]
m
in r+ i' in 5̂' 10 0)
CO 3 Q.
0)
0) Q.
0)
.£> c (D
3
O O o Q
. in tn
o r+ 3"
(D
» f*
0) -i
3 CD a CD in
Q10
0A
RE
ASL
OPE
ELEV
|
PRE
C
| IN
T |
OR
GSH
APE
|
LON
G
| FO
RS
| EV
AP
LAT
DG
OC
D
GO
M
LEN
G
DA
TUM
Low
- to
mid
dle-
elev
atio
n re
gion
s (8
87 s
tatio
ns)
Q10
0A
REA
SLO
PEEL
EVPR
ECIN
TO
RG
SHA
PELO
NG
FOR
SEV
AP
LAT
DG
OC
DG
OM
LEN
GD
ATU
M
1.00 .6
6-.
56-.
13-.
05 .17
.28
.09
-.29
-.05 .3
5-.
43-.
36-.
42 .67
-.31
1.00
-.62
.25
.20
-.18 .1
4-.
07-.
17 .24
-.14 .0
9.1
4-.
09 .96
-.01
1.00 .13
.19
.21
-.19
-.08 .2
7.2
0-.
12 .11 .08
.27
-.63 .14
1.00 .58
1.00
-.21
.1
9 1.
00.0
3 .0
4 .0
7 1.
00-.
10
-.11
.0
1 .1
0-.
19
-.06
.0
8 -.
28.6
5 .6
0 .0
2 .0
7-.
59
-.52
.43
.03
.38
.30
-.57
-.
16.5
1 .3
2 -.
54
-.15
.05
.09
-.24
-.
26
.22
.17
-.18
.1
7.8
9 .4
5 -.
28
.00
1.00
-.19
1.
00-.
11
-.04
1.
00.1
6 -.
21
-.47
1.
00-.
15
.40
.26
-.82
1.
00-.
12
.21
.34
-.76
.9
2 1.
00-.2
1 .8
7 .1
0 -.5
3 .7
4 .5
2 1.
00.1
9 -.2
1 .2
1 -.
08
.04
.09
-.14
1.
00-.
12
-.16
.5
4 -.
60
.39
.50
.08
-.04
1.
00H
igh-
elev
atio
n re
gion
(17
2 st
atio
ns)
Q10
0A
REA
SLO
PEEL
EVPR
ECIN
TO
RG
SHA
PELO
NG
FOR
SEV
AP
LAT
DG
OC
DG
OM
LEN
GD
ATU
M
1.00 .87
-.62 .2
0.2
6-.
22 .30
-.03
-.12
-.06
-.19 .0
3.0
5-.
04 .81
-.34
1.00
-.74 .1
8.1
3-.
40 .21
.02
-.21
-.03
-.24 .0
7.1
2-.
07 .95
-.38
1.00 .17
.11 .44
-.08
-.21 .04
.17
.22
-.18
-.16
-.09
-.77 .2
8
1.00 .2
4 1.
00.0
8 .2
8 1.
00.0
2 .2
8 .3
4 1.
00-.
19
-.21
-.
11
-.19
-.52
.20
.08
-.12
.02
.14
.10
-.06
.03
-.43
.3
1 -.
10-.
41
.11
-.47
-.
22
-.29
.0
6 -.
55
-.23
-.50
.11
-.25
-.
21.1
2 .0
6 -.
41
.14
.61
-.02
.2
4 -.
15
1.00 .15
1.00
.00
-.05
1.00
.08
-.26
.1
0 1.
00.0
5 .5
8 -.
12
-.63
1.
00-.
02
.34
-.11
-.56
.9
4 1.
00.1
2 .8
7 -.
10
-.50
.8
9 .7
2 1.
00.3
3 -.1
5 -.
04
-.21
.08
.11
.03
1.00
-.18
-.
36
-.02
.1
8 -.4
3 -.
37
-.41
-.41
1.00
Table 28. Stepwise ordinary least-squares regression of 7-year discharge and basin and climatic characteristics for the entire low- to middle-elevation study area
[The stepwise regression equations are based on 819 gaged sites. All variables are log-transformed except ORG. AREA, drainage area, in square miles; LAT, latitude of gaged site, in decimal degrees minus 28; ORG, orographic factor is an integer attribute ranging from -3 to +3; ELEV, mean basin elevation, in thousands of feet above sea level; DOOM, distance from Gulf of Mexico, in hundreds of miles; PREC, mean annual precipitation, in inches; SHAPE, shape factor of drainage basin, dimensionless; and INT, precipitation intensity for 24-hour, 100-year recurrence interval, in inches]
Recur rence
interval (yesrs)
10
100
Regression coefficients
Con stant
1133,5203,0502,1002,640
10,9006,650
35225,90022,20031,100 22,40010,50010,00023,200
AREA
0.56.60.58.59.60.60.60.52.56.54.56 .56.57.58.58
LAT
--1.6-1.5-1.5-1.4-.98-.58-
-2.0-1.9
-1.7 -1.7-1.5-1.4-1.0
ORG
--
0.083.077.082.069.065
-
0.088.096 .091.091.092.082
SHAPE
---
0.21.20.17.18
- -
.18
.20
.19
.18
ELEV DGOM
..
-0.31-.47 -0.81-.59 -1.2
.. ..
-0.48 -.47-.50-.30
-.44 -.65
Stsndsrd error of
INT PREC estimste (percent)
1339997969594
0.51 - 93165113110108 107
0.34 107.63 -0.35 106.78 -.37 106
(the coefficient of variation is constant at all stations); therefore, a single-probability distribution can be fit to the composite record. In the hybrid and station- year methods, spatial sampling is assumed to be equivalent to time sampling if the records are inde pendent. Thus, a combination of 10 records, each with 10 years of record, results in a 100-year com posite record. A complete description of the hybrid method and associated assumptions is given in Hjalmarson and Thomas (1992).
The hybrid method incorporates the station-year approach to produce regional flood-frequency rela tions based on basin and climatic characteristics. Wahl's (1982) application of a modified station- year approach to a semiarid region in Wyoming standardized the logarithms of annual peak dis charges by dividing by the mean of the logarithms of the peaks. Wahl (1982) noted, however, that in a record containing many years of no flow, the average becomes a meaningless statistic and a new
standardization technique is needed. The hybrid method addresses the problem of no-flow years in flood records, a common problem in the south western United States. The method reduces flood records to a common base by dividing annual peaks by a function of common hydrologic characteristics.
In the hybrid method, records of annual peak discharges from gaging stations are combined into three or more levels of a common basin characteris tic, such as drainage area. For this study, each level had at least 100 annual peaks to avoid extrapolation to the 100-year flood and to allow for application of the Weibull plotting-position formula. Annual peak discharges within each level are standardized using an approximate factor and combined to form a single composite record as in the station-year method. The standardizing factor is refined with an iterative technique that uses regression and flood-frequency analysis. Standardized flood- frequency relations are determined for each basin-
Regionsl Anslysis 97
characteristic level at each iteration, and regional flood-frequency relations using basin and climatic characteristics are determined at the final iteration.
Drainage area is the first characteristic used for the iterative technique, and additional character istics are individually added using the same iterative technique to yield the final regional relation. Addi tional characteristics are added only if they significantly (cc<0.05) reduce the standard error of regression of the regional relation. The explanatory variables used in the four regions with hybrid rela tions (Regions 6, 10, 11, and 16) are drainage area, mean basin elevation, and mean annual evaporation.
A major advantage of the hybrid method is that no extrapolation is needed for the flood probability of interest, assuming independence of peak- discharge data, and elementary plotting-position formulas can be used to define flood-frequency relations. Because little is known about how to obtain valid estimates of probability for the many ephemeral streams of the more arid regions of this study, the probabilities were simply computed using the Weibull plotting-position formula. The use of the Weibull method with the compositing of records avoids the problem of attempting to fit a smooth curve through the data.
1,000,000
100,000
o oLU 03ccLUa.I-01 LU U-OCD O O
LU CD CC < I O 03 Q
LU 0.
10,000
1,000
100
10
........ AVERAGE NORTHERN RELATION (REGIONS 2-4)
- - - AVERAGE MIDDLE RELATION (REGIONS 5-9, 15)
AVERAGE SOUTHERN RELATION (REGIONS 10-14, 16)
RANGE OFMIDDLE
RELATIONS
RANGE OF>SOUTHERN
RELATIONS
1 RANGE OF ^NORTHERN
J RELATIONS
0.1 10 100
DRAINAGE AREA, IN SQUARE MILES
1,000 10,000
Figure 66. Relation between 100-year peak discharge and drainage area for the northern, middle, and southern parts of the study area.
98 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
In the application of the hybrid method to a particular region, three assumptions need to be evaluated; the annual peaks at gaging stations should be independent, and the explanatory variables should be independent and normally dis tributed. The sample of gaging stations and peak discharges in the four arid regions with hybrid relations in this study (6, 10, 11, and 16) appear to meet the assumption of independence. Significant floods did not tend to occur in the same years at most sites. The gaged sites generally are far apart, and most have small drainage areas. The median drainage area of the gaged sites is about 11 mi2 , and about two-thirds of the sites have a drainage area of less than 50 mi2 . Smaller drainage areas would be less likely to experience the same storms that produce the annual peaks. About 60 percent of the annual peaks are caused by summer thunder storms, which generally have a small areal extent and occur in an erratic fashion. Independence of the samples of log-transformed explanatory variables is indicated because of small correlation coefficients (r); drainage area and mean basin elevation in Region 6 have an r value of 0.19, drainage area and mean annual evaporation in Region 11 have an r value of -0.06, and drainage area and mean annual evaporation in Region 16 have an r value of 0.21. The explanatory variables are distributed fairly evenly through their range of values (figs. 29, 37, 38, and 48), and boxplots of the log-transformed variables appear normal.
For regions where most station flood-frequency relations can be defined, the hybrid method and the station-relation regression method (GLS) produce regional relations with similar coefficients, but the standard errors of estimate are computed differently and thus the magnitudes of the errors are different. Standard errors for GLS relations are similar to the well-known OLS standard errors, and the differ ences between OLS and GLS errors are explained in Stedinger and Tasker (1985). A discussion of how hybrid error is computed is found in Hjalmarson and Thomas (1992), and a brief expla nation is given here.
The standard errors of the hybrid relations for Regions 6, 10, 11, and 16 are much larger than the standard errors of GLS relations for the remaining regions. The ratio of the average hybrid error to the average error of the GLS relations is more than 10 for Region 6, about 6 for Region 10, and less than 2 for Regions 11 and 16. Two basic reasons for this
difference are that the two methods have computa tional differences and are applied to regions with different flood characteristics.
The average standard error of regression in the hybrid method is estimated using a variation of a direct assessment procedure where subsets of station records are randomly selected without replacement, estimates of 7-year discharge are made for each subset of stations, the sample variance of the estimates of 7-year discharge is computed, and the population variance or standard error is com puted using a relation between the variance about the mean value of 7-year discharge for a region and the variance about the mean value of 7-year dis charge for a sample. In this study, thirty subsets of stations were selected for each step of the error analysis.
The hybrid errors are larger than the GLS errors because the hybrid errors include much of the within-station residual variance, which is the variance of annual peak discharges about the flood- frequency relation that is fitted to the record at a particular gaging station. The GLS method takes into account the fact that stations in a region have unequal lengths of record, which results in esti mates of 7-year discharges with unequal variances; however, all the variance associated with the fitting of a relation to peak discharges at a particular gag ing station is not taken into account in GLS errors.
The hybrid errors are larger than the GLS errors in this report because the hybrid relations are applied to four regions with more variable flood characteristics than the 12 GLS regions. The magni tude of the hybrid errors is closely related to the variability of the annual peak discharges and the percentage of undefined station flood-frequency relations in a region. The largest hybrid errors are in Regions 6 and 10, and the hybrid errors for Regions 11 and 16 are of moderate magnitude. The average standard deviation of peak discharges in gaging-station records is about 0.9 log units for Regions 6 and 10, 0.5 log units for Regions 11 and 16, and 0.4 log units for the 12 GLS regions. The average percentage of undefined station flood- frequency relations is about 55 percent for Regions 6 and 10, 30 percent for Regions 11 and 16, and 11 percent for the 12 GLS regions. The hybrid relations are developed from all station records in the regions, and the GLS relations are developed from only the stations with defined flood-frequency relations.
Regional Analysis 99
Table 29. Summary of estimated prediction errors of generalized least-squares regional models
[Recurrence interval, in years: PE, the estimated average standard error of prediction from calibration of generalized least-squares model, in percent; PES, the estimated average prediction error from split-sample analysis, in percent. Number of stations is the total number of stations in region used for regression analysis]
Region
123457891213
1415
Numbar of
stations
165108351083728
1084368
73
2217
Recurrence interval,
PE
59728664
135567268
10557
7464
2
PES
64767466151758187
88
51
5175
5
PE
52668357101456255
68
406366
PES
55656756123646960
5736
3480
10
PE
4861805384455752
52
376568
PES
52656454115626551
5038
2884
in yeara
25
PE
4661785187495453
4039
6371
PES
52686253109526148
50
47
2993
50
PE
4664775291535357
37
436473
PES
52706153107526048
58
55
25101
100
PE
4668785395595359
39
486676
PES
54746254105556053
6364
25111
The large errors of the hybrid relations in Regions 6 and 10 indicate that much of the varia tion in flood characteristics remains unexplained by the relations; therefore, those relations must be con sidered as only rough estimates. The magnitude of the errors is too large to have much meaning, but it does show the relative differences between relations for the different recurrence intervals. GLS relations were not determined in those regions because they would be based on less than half the available peak- discharge information.
Transition Zones
At most ungaged sites in the study area, flood- frequency relations can be estimated using the single set of regression equations for the flood region in which the site is located. When a site is near a regional boundary, however, a weighted esti mate of peak discharge may be more appropriate. Computed peak discharges from the equations of two adjacent regions may be quite different for a site near a boundary. Two transition zones are defined in this report where methods are provided
to weight estimated flood-frequency relations: (1) sites with a drainage area in two low- to middle-elevation regions and (2) sites in a low- to middle-elevation flood region where the basin is near the boundary of the high-elevation region.
Weighted flood-frequency relations for sites with a drainage area in two low- to middle- elevation regions are computed using the percentage of the drainage area in each region (equation 6). Peak discharges are estimated for each region as if the drainage area were entirely in one region, and then the weighted average of these discharges is computed.
Weighted flood-frequency relations for sites in a low- to middle-elevation flood region with an elevation that is within 700 ft of the boundary of the high-elevation region are computed using equation 7. Equation 7 is an averaging procedure based on how the elevation of the study site fits into the elevation boundaries of the 700-foot tran sition zone. Peak discharges are estimated for each region as if the drainage area were entirely in one region, and then the weighted average dis charge is computed. The weighted discharges are close to the low- to middle-elevation models near the lower part of the transition zone and close to
100 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
the high-elevation model near the upper part of the transition zone.
The selection of the 700-foot transition zone was made by comparing residuals computed from the low- to middle-elevation regional models with those from the high-elevation regional models. Gaged sites were placed into four groups with gaged-site elevations between the boundary of the High-Elevation Region 1 and 500, 700, 1,000, and 1,200 ft below that boundary. The 100-year peak-discharge equations for the appropriate low- to middle-elevation regions and the high- elevation region were then used to compute residuals for each site (table 30). The mean and median of the residuals should ideally be zero, which would indicate no bias, and the magnitude of the standard deviation indicates the accuracy. The low- to middle-elevation models have a slight positive bias for all groups, and the high-elevation model has a slight negative bias for all groups. As the transition zone becomes larger and more lower elevation sites are added to the groups, the bias becomes smaller and the standard deviation remains about the same for the low- to middle-elevation models. Bias and standard deviation become larger for the high-elevation model. These comparisons indicate that as the transition zone gets larger, the low- to middle-elevation models get slightly better; however, the high-elevation model becomes more biased and less accurate.
The criterion for selecting the most appropri ate size of a transition zone was based on the composite residuals in table 30. For each site, an average predicted 100-year peak discharge was computed using the predicted discharges from the appropriate low- to middle-elevation model and the high-elevation model. The composite residual is the average predicted discharge minus the sta tion value of the discharge. The best transition zone, therefore, has the smallest bias and smallest dispersion of composite residuals. The transition zone of 700 ft was selected for this study because the mean and median composite residuals are closest to zero and the standard deviation of the composite residuals is similar to the other three transition zones (table 30).
Two statistical tests were made to compare the central tendency or bias of the composite residuals in the four transition zones. The hypoth esis that the mean is equal to zero was tested with a f-test, and the mean of the residuals is
significantly different than zero for the zones of 1,000 and 1,200 ft (a<0.05). The hypothesis that the median is equal to zero was tested with a Wilcoxon signed rank procedure. None of the transition zones had a median that was significantly different than zero. The 700-foot zone, however, has the largest alpha value; the alphas for the zones are 0.23 for 500 ft, 0.87 for 700 ft, 0.15 for 1,000 ft, and 0.06 for 1,200 ft (Minitab, 1988, p. 97, 191- 192).
ADDITIONAL DATA AND STUDY NEEDS
A better understanding of flood characteristics is needed for flood-frequency studies in the southwestern United States. Because streamflow is extremely variable, data obtained from the sparse area! distribution of gaging stations and the short records at many stations commonly result in samples that do not represent the populations of floods that occur in the area. More streamflow- and crest-stage gaging stations throughout the study area that have longer records would provide an im proved data base. Crest-stage stations are an efficient method for obtaining records of annual maximum peak discharges, and more peak- discharge information is needed especially in the low- to middle-elevation areas where streamflow is more variable. Existing peak-discharge records could be augmented by historical information. Such information is obtained from newspapers and other cultural information, from observation of mudlines after peak flows, from records of bridge and culvert construction, and from paleoflood investigations.
Statistical and probability analyses commonly are used to estimate flood-frequency relations at gaged and ungaged sites. More research is needed on which probability distributions are applicable to streams in arid areas. The analysis of regional skew coefficient in this study indicated that the log- normal distribution may be applicable to many sites in the study area.
The hybrid method developed during this study uses elementary plotting-position formulas to esti mate regional flood-frequency relations. Thus, it avoids the potential problem of fitting an incorrect probability distribution to the data. The method combines elements of the station-year method and multiple-regression analysis to determine regional
Additional data and study needs 101
relations directly from the peak-discharge data. The method, however, assumes independence of the peak discharges, and the explanatory variables should be independent and normally distributed. More evaluation of the potential effects of depen dence or nonnormality on hybrid coefficients and errors is needed.
The large errors of the hybrid relations in Regions 6 and 10 indicate that much of the varia tion in flood characteristics remains unexplained by the relations. These two regions have the most arid climate in the study area. Reliable flood-frequency relations are difficult to define at many gaging stations because the available records have many years with no flow and a large variability of the peak discharges. More studies are needed in those regions to find alternative methods of estimating flood-frequency relations. Commonly used statistical methods that are based on station flood-frequency relations do not appear to be well suited to such areas. The hybrid method, which does not use station flood-frequency relations, needs to be developed and refined. Other new methods with perhaps a multidiscipline approach need to be investigated.
Two methods are commonly used for esti mating flood-frequency relations at ungaged sites (1) transferring flood-frequency relations from gaged to ungaged sites by multiple- regression or index-flow techniques and (2) esti mating runoff by applying a rainfall intensity of a specific probability to a deterministic or empiri cal rainfall-runoff model. Both methods would benefit from additional precipitation data, espe cially in middle- to high-elevation areas. A definition of precipitation intensity for specific recurrence intervals could be obtained from such data. Additional data and information that are needed for the information-transfer method used in this report include more explanatory variables to define the variation in basin and flood charac teristics of the southwestern United States. Some potentially significant basin characteristics in clude soils, geologic material, vegetation, and drainage network.
The technology used in geographic-informa tion systems has a potential for determining new explanatory variables. In this study, values of maximum precipitation intensity, mean annual evaporation, potential natural vegetation, and oro- graphic influence were determined for gaged-site
locations using geographic-information-systems technology, and all characteristics except poten tial natural vegetation were significantly related to flood characteristics. When drainage-area boundaries for the gaging stations are defined in a geographic-information system, significant information would be available to develop future studies and models. The use of geographic- information-systems technology to more uni formly redefine explanatory variables, such as mean basin elevation and mean annual precipita tion, also has potential for improving regional flood-frequency relations.
The sample of gaging stations used in this study did not represent some of the hydrologic conditions that exist in the study area. Streams in permeable volcanic or limestone terrain, distributary-flow areas (such as active alluvial fans), and playas were not adequately sampled. Transferring flood informa tion from gaged to ungaged sites may be inadequate in low- or middle-elevation sites in deserts where the drainage area is large and where a large peak- discharge attenuation often occurs. Investigations of flood-frequency characteristics in the areas where flood magnitude decreases along the stream as drainage area increases would add significantly to future studies.
Peaks at miscellaneous sites were excluded from this study because some extreme peaks at ungaged sites in the study area have been found to be erroneous. Some extreme peaks in the arid southwestern United States that were estimated using indirect methods such as the slope-area method probably were debris flows. The slope-area method is inappropriate for these non-Newtonian flows and commonly greatly overestimates the peak discharge. The drainage-basin area for some miscel laneous sites was determined several years ago from small-scale topographic maps, and these computed areas may have large errors. A review of indirect measurements for the extreme peaks is needed, including an examination of photographs for evidence of debris flows and recomputation of the drainage basins using the latest topographic maps.
SUMMARY
The general magnitude of peak discharges in the southwestern United States decreases in a north ward direction. In the southern part of the area
102 Methods for Estimating Magnituda and Frequancy of Floods in tha Southwastern United States
(between 29° and 37° latitude), the mean maximum unit-peak discharge of record is 316 (ft3/s)/mi2 . In contrast, the mean maximum unit-peak discharge of record is 26 (ft3/s)/mi2 in the northern part of the area (between 41° and 45° latitude).
An elevation threshold exists in the study area where large floods caused by thunderstorms rarely occur above that threshold. For sites between 29° and 41° latitude, the elevation threshold is approxi mately 7,500 ft above sea level. Between 41° and 45° latitude, the elevation threshold decreases in a northward direction at a rate of about 300 ft for each degree of latitude. For example, at 42° lati tude, the threshold is 7,200 ft, and at 43° latitude, the threshold is 6,900 ft.
Detailed flood-frequency analyses were made of more than 1,300 gaging stations with a combined 40,000 station years of annual peak discharges. The LPIII probability distribution and the method of moments were used to define flood-frequency rela tions for most gaging-station records. The reliability of station flood-frequency relations was assessed by visual examination of how well the computed rela tions fit the plotted peak discharges, the presence or absence of outliers, and the shape exhibited by the plotted peaks.
Generally, the computed flood-frequency rela tions agreed well with the plotted peak discharges. A low-discharge threshold was applied to about one-half of the sites to adjust the relations for low outliers. With few exceptions, the use of the low- discharge threshold resulted in markedly better appearing fits between the relations and the peak- discharge data. About one-third of the sites had a high outlier, or an odd-appearing shape of the plot ted peaks such as a discontinuity or a sharp break; however, these sites were judged to have adequate fits and the computed relations were used. The indi vidual flood-frequency relations for 264 of the sites were judged to be unreliable because of extremely poor fits of the computed relations to the peak- discharge data. The sites may have had inadequate samples to define a relation or non-LPIII probabil ity distributions; therefore, the computed relations at these sites were not used in the standard regional analysis on the basis of station flood-frequency relations. Peak-discharge records at the 264 sites that had unreliable relations are extremely variable and had an average standard deviation of 0.88 log units. Most of the 264 sites were from extremely arid areas. One hundred and twelve (42 percent) of
the sites had more than 25 percent of the annual records with no flow.
The hybrid method developed during this study was used to define regional relations in the arid regions, where there were many years of no flow at the gaging stations and where many of the station relations were unreliable. A major advantage of the new hybrid method, which has no extrapolation to the recurrence interval of interest assuming independence of the data, is that elementary plotting-position formulas can be used to define the regional flood-frequency relations. The hybrid method uses all of the available peak-discharge data in the extremely arid regions, while the standard method that is.based on station flood- frequency relations uses only the defined station relations. Data in station records with undefined flood-frequency relations are not used.
A mixed-population analysis was performed on a sample of 51 gaging stations with peaks caused by snowmelt and summer thunderstorms. Significant differences were not found between flood-frequency relations computed from the mixed populations and from composite relations computed by separating the peaks, computing separate rela tions, and combining the separate relations.
An analysis of regional skew coefficient was made for the study area. The methods of attempting to define the variation in skew by geographic areas or by regression with basin and climatic characteris tics all failed to improve on a mean of zero for the sample. The regional skew used in the study, there fore, was the mean of zero with an associated error equal to the sample variance of 0.31 log units.
The regional analysis consisted of an investiga tion of different forms of models, the significance of all available explanatory variables, and the geo graphic variation of flood magnitudes at selected recurrence intervals. The geographic variation of flood characteristics was explained by dividing the study area into 16 flood regions. A high-elevation region was defined for the entire study area with the lower boundary coinciding with the elevation threshold for large floods caused by thunderstorms.
The model that best describes most regional flood-frequency relations for this study area is the multiplicative model, where all variables are log-transformed. Eighteen of the 19 investigated explanatory variables were significantly related to flood characteristics in some part of the study area; however, only drainage area, mean basin elevation,
Summary 103
Table 30. Summary of residuals from low- to middle-elevation regional models, the high-elevation model, and a composite model for gaged sites in a transition zone
[Transition zone The zone includes gaged sites with elevations between the boundary of the high-elevation region and 500, 700, 1,000, and 1,200 feet below that boundary. Composite model A composite 100-year peak discharge is computed by taking the average of the predicted discharge from the appropriate low- to middle-elevation model and the high-elevation model. The composite residual is the composite discharge, in log units, minus the station discharge, in log units]
Regression residuals from 100-year peak-dischsrge models, In log units
Transi tion
zone, in feet
500
700
1,000
1,200
Num ber of sites
64
100
162
198
Low- to middle-elevation models
Mesn
0.14.11
.09
.09
Median
0.10
.07
.06
.06
Stan dard
devia tion
0.36
.36
.35
.34
High-elevation model
Mean
-0.08-.15
-.23
-.24
Median
-0.02-.03
-.10
-.10
Stan dard
devia tion
0.45.50
.53
.54
Composite model
Mesn
0.03-.02
-.07
-.08
Median
0.04
.00-.02
-.02
Stan dard
devia tion
0.35
.38
.39
.39
mean annual precipitation, mean annual evapora tion, latitude, and longitude are needed to use the regional models.
GLS regression was used to define the regres sion models in 12 regions where sufficient data allowed a reasonable regional model to be devel oped using the flood-frequency relations at gaged sites. Four regions had more than 30 percent of the gaged sites with no defined relations; therefore, the regression method was not used because of the large amount of missing information. The hybrid analysis was used in those four regions because the method does not use station flood-frequency rela tions and the method uses all the data from gaging stations in a region. The average standard error of prediction in the 12 regions with GLS models ranged from 39 to 95 percent for the 100-year peak discharge, and only three of these models had errors of greater than 70 percent. The estimated average standard error in the four regions with hybrid models, computed differently than the GLS errors, ranged from 0.442 to 1.84 log units for the 100-year peak discharge.
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Fletcher, J.E., Huber, A.L., Haws, F.W., and Clyde, C.G., 1977, Runoff estimates for small rural water sheds and development of a sound design method, volume II, Recommendations for preparing design manuals and appendices B, C, D, E, F, G, and H: Federal Highway Administration Report FHWA- RD-77-159, 368 p.
Fuller, J.E., 1987, Paleoflood hydrology of the alluvial Salt River, Tempe, Arizona: Tucson, University of Arizona, master's thesis, 70 p.
Fuller, W.E., 1914, Flood flows: American Society of Civil Engineers, Transactions, v. 77, no. 1293, p. 564-617.
Hardison, C.H., 1971, Prediction error of regression estimates of streamflow characteristics at ungaged sites: U.S. Geological Survey Professional Paper 750-C, p. C228-C236.
Harenberg, W.A., 1980, Using channel geometry to esti mate flood flows at ungaged sites in Idaho: U.S. Geological Survey Water-Resources Investigations Report 80-32, 39 p.
Harris, D.D., and Hubbard, L.E., 1982, Magnitude and frequency of floods in eastern Oregon: U.S. Geo logical Survey Water-Resources Investigations Report 82-4078, 45 p.
Hedman, E.R., Moore, D.O., and Livingston, R.K., 1972, Selected streamflow characteristics as related to channel geometry of perennial streams in Colorado: U.S. Geological Survey Open-File Report 72-1060, 24 p.
Hedman, E.R., and Osterkamp, W.R., 1982, Streamflow characteristics related to channel geometry of streams in Western United States: U.S. Geological Survey Water-Supply Paper 2193, 17 p.
Hejl, H.R., Jr., 1984, Use of selected basin charac teristics to estimate mean annual runoff and peak discharges for ungaged streams in drainage basins containing strippable coal resources, northwestern New Mexico: U.S. Geological Survey Water- Resources Investigations Report 84-4260, 17 p.
Hjalmarson, H.W., 1991, Flood hydrology of arid basins in southwestern United States, in Kirby, W.H., and Tan, W.Y., compilers, Proceedings of the United States People's Republic of China Bilateral Sympo sium on droughts and arid-region hydrology, September 16-20, 1991, Tucson, Arizona: U.S. Geo logical Survey Open-File Report 91-244, p. 59-64.
Hjalmarson, H.W., and Kemna, S.P., 1991, Flood hazards of distributary-flow areas in southwestern Arizona: U.S. Geological Survey Water-Resources Investigations Report 91 4171, 58 p.
Hjalmarson, H.W., and Thomas, B.E., 1992, A new look at regional flood-frequency relations for arid lands: American Society of Civil Engineers, Journal of Hydraulic Engineering, v. 118, no. 6, p. 868-886.
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Hulsing, H., and Kallio, N.A., 1964, Magnitude and frequency of floods in the United States Part 14. Pacific Slope basins in Oregon and lower Columbia River basin: U.S. Geological Survey Water-Supply Paper 1689, 320 p.
Interagency Advisory Committee on Water Data, 1982, Guidelines for determining flood flow frequency: Washington, D.C., Interagency Advisory Committee on Water Data, Hydrology Subcommittee Bulletin 17B, 183 p.
Jarrett, R.D., 1987, Flood hydrology of foothill and mountain streams in Colorado: Fort Collins, Colo rado State University, Ph.D. dissertation, 239 p.
Jarrett, R.D., and Costa, I.E., 1982, Multidisciplinary approach to the flood hydrology of foothills streams in Colorado, in Johnson, A.I., and Clark, R.A., eds., International Symposium on Hydrometeorology: Bethesda, Md., American Water Resources Associa tion, p. 565-569.
Kircher, J.E., Choquette, A.F., and Richter, B.D., 1985, Estimation of natural streamflow characteristics in western Colorado: U.S. Geological Survey Water- Resources Investigations Report 85-4086, 28 p.
Kjelstrom, L.C., and Moffatt, R.L., 1981, Method of estimating flood-frequency parameters for streams in Idaho: U.S. Geological Survey Open-File Report 81-909, 101 p.
Kochel, R.C., 1980, Interpretation of flood paleo- hydrology using slackwater deposits, lower Pecos and Devils Rivers, southwestern Texas: Austin, University of Texas, Ph.D. dissertation, 364 p.
Kuchler, A.W., 1964, Potential natural vegetation of the conterminous United States: American Geographical Society Special Publication 36, 116 p.
Leavesley, G.H., Lichty, R.W., Troutman, B.M., and Saindon, L.G., 1983, Precipitation-runoff modeling system User's manual: U.S. Geological Survey Water-Resources Investigations Report 83-4238, 207 p.
Lowham, H.W., 1976, Techniques for estimating flow characteristics of Wyoming streams: U.S. Geological Survey Water-Resources Investigations Report 76-112, 83 p.
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Massey, B.C., and Schroeder, E.E., 1977, Application of a rainfall-runoff model in estimating flood peaks for selected small natural drainage basins in Texas: U.S. Geological Survey Open-File Report 77-792, 34 p.
McCain, J.F., and Jarrett, R.D., 1976, Manual for esti mating flood characteristics of natural-flow streams in Colorado: Denver, Colorado Water Conservation Board Technical Manual No. 1, 68 p.
McGinn, R.A., 1980, Discussion of flood frequency estimates on alluvial fans: American Society of Civil Engineers, Journal of the Hydraulics Division, v. 106, no. HY10, p. 1718-1720.
Miller, J.F., Frederick, R.H., and Tracey, R.J., 1973a, Precipitation-frequency atlas of the Western United States Volume II, Wyoming: National Oceanic and Atmospheric Administration NOAA Atlas 2, 43 p.
1973b, Precipitation-frequency atlas of the West ern United States Volume III, Colorado: National Oceanic and Atmospheric Administration NOAA Atlas 2, 43 p.
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Minitab, 1988, Minitab reference manual Release 6.1: State College, Penn., Minitab, Inc., 341 p.
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106 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
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108 Methods for Estimating Magnitude and Frequency of Floods in tha Southwestern United States
BASIN, CLIMATIC, AND FLOODCHARACTERISTICS FOR STREAMFLOW-
GAGING STATIONS IN SOUTHWESTERN UNITEDSTATES
The data in the following section and the annual peak-discharge data used in thisstudy may be accessed on the Internet at the following address:
http://h2o.er.usgs.gov/public/nawdex/o93-419.html
109
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES
Peak discharge: First line, station value used in regression analysis, and second line, value weighted with station and regional value. For stations with no defined relation, second line, regional value of peak discharge.
Dashes indicate no data.
Station number
0720*000
07204500
07205000
07206400
07214500
07214800
07217000
07217100
08216500
08218000
08218500
08219500
08220500
08223500
08224500
08227000
08227500
08230500
08231000
08236000
08240500
08241000
08241500
08242500
08245500
08246500
08247500
08248000
Station name
Moreno Creek at Eagle Nest, N. Hex.
Cieneguilla Creek nearEagle Nest, N. Max.
Six Mile Creek nearEagle Nest, N. Mex.
Clear Creek near Ute Park, N. Mex.
Mora River near Holman, N. Mex.
Rio La Casa nearCleveland, N. Mex.
Coyote Creek below Black Lake,N. Mex.
Coyote Creek above Guadalupita,N. Mex.
Willow Creek at Creed, Colo.
Goose Creek nearWagonwheel Gap, Colo.Goose Creek atWagonwheel Gap, Colo.
South Fork Rio Grande atSouth Fork, Colo.
Pinos Creek near Del Norte, Colo.
Rock Creek near Monte Vista, Colo.
Kerber Creek at AshleyRanch, near Villa Grove, Colo.
Saguache Creek near Saguache, Colo.
North Crestone Creek nearCrestone, Colo.
Carnero Creek nearLa Garita, Colo.
La Garita Creek nearLa Garita, Colo.
Alamosa Creek above TerraceReservoir, Colo.Trinchera Creek above TurnersRun, near Ft. Garland, Colo.Trinchera Creek above Mountain HomeReservoir near Ft. Garland, Colo.
Sangre De Cristo Creek nearFt. Garland, Colo.
Ute Creek near Ft. Garland, Colo.
Conejos River at Platoro, Colo.Platoro, Colo.
Conejos River near Mogote, Colo.
San Antonio River at Ortiz, Colo.
Los Pinos River near Ortiz, Colo.
Flood region
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude , in decimal degrees
36
36
36
36
35
35
36
36
37
37
37
37
37
37
38
38
38.
37.
37.
37,
37,
37.
37.
37.
37.
37.
36.
36.
.554
.485
.519
.526
.110
.974
.272
.164
.856
.687
.752
.657
.592
.490
.241
.163
.014
.860
.813
.375
.375
395
425
447
354
054
993
982
Longi
tude , in decimal degrees
105
105
105
105
105
105
105
105
106
106
106
106
106
106
106
106
105
106
106
106,
105,
105.
105.
105.
106.
106.
106.
106.
.267
.265
.275
.175
.376
.389
.247
.230
.927
.889
.829
.649
.449
.259
.116
.290
.692
.319
.318
,334
,294
,369
,414
.425
.524
187
038
073
Mean System- basin atic Drainage eleva- years area, in tion, of square in
record miles feet
49
48
52
23
21
14
12
17
32
15
31
63
47
25
49
71
46
57
60
54
59
32
58
59
14
43
62
68
73.80
56.00
10.50
7.44
57.00
23.00
48.00
71.00
35.30
53.60
90.00
216.00
53.00
32.90
38.00
595.00
10.70
117.00
61.00
107.00
45.00
61.00
190.00
32.00
44.40
282.00
110.00
167.00
10,200
9,400
9,500
9,770
10,000
9,000
9,300
9,420
11,500
11,000
10,700
10,400
10,500
10,400
10,500
10,200
11,300
10,100
10,100
11,000
10,400
10,000
9,200
10,000
11,200
10,300
9,500
9,900
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
20.0
19.0
20.0
17.0
22.0
24.0
19.0
19.0
24.0
28.0
26.0
30.0
30.0
15.0
19.0
16.0
20.0
20.0
18.0
29.0
22.0
18.0
15.0
16.0
35.0
26.0
11.0
24.0
45.0
44.9
44.9
45.0
53.3
44.6
43.9
44.7
35.0
35.0
35.0
37.9
40.2
40.1
35.3
39.6
41.2
41.0
42.3
35.0
45.2
47.3
46.5
45.4
35.0
41.6
47.0
46.2
110 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES
Relation characteristic: L, low-discharge threshold used to compute station relation; H, high outlierdetected in station record; D, relation fit through the plotted annual peak flows has the appearance of a dogleg or jump; 0, station is regional outlier deleted from generalized least-squares regression analysis; U, relation was undefined. 1, code applies; 0, code does not apply; and -, code is not applicable.
Station number
07204000
07204500
07205000
07206400
07214500
07214800
07217000
07217100
08216500
08218000
08218500
08219500
08220500
08223500
08224500
08227000
08227500
08230500
08231000
08236000
08240500
08241000
08241500
08242500
08245500
08246500
08247500
08248000
Relation characteristic L H D 0 U
1
1
0
0
0
0
1-
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
1
0
0
1
1
0
0
0
0
0
1
0
-
0
0
0
1
0
0
0
0
1
0
0
1
1
0
1
1
0
1
0
0
0
1
0
0
0
0
0
-
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
7172
12212228282020
5605581931934245
316190190418418371372
1,5101,510
17617786869394
3263298484
139140158158944944114114114115158159143143
1,0301,0202,6402,640
505504
1,3801,380
5
12112724324555564545
1,6301,600
449442178188 --
531301303701699559566
2,3502,350
304309148150156158529545149149322328291293
1,4001,400
217219228232350356215215
1,2201,2003,6603,640
819815
1,9001,900
10
15917534535179816870
2,8602,730
717685394405
685377382920910691709
2,9702,960
402414192197206212669714208207501514395399
1,7301,720
305310322332536551267268
1,3301,2904,4004,3501,0401,0302,2302,220
feet per second) for interval (years)
25
212248497509117121106110
5,2304,7601,2101,100
952901
886476487
1,2301,190
863901
3,8203,790
538563249263277290850955304299803826540549
2,1802,160
441452457479847876335338
1,4601,3905,4205,3001,3501,3302,6502,630
50
256311626642151157142146
7,7206,7901,7101,4801,7101,500
1,040550567
1,4901,420
9951,0504,5104,450
648682292315336356986
1,150395386
1,0901,120
658670
2,5502,510
560574568599
1,1401,180
389395
1,5501,4706,2406,0601,5801,5502,9602,930
100
302378768786190193184187
11,0009,3602,3501,9502,9402,410
1,190624647
1,7601,6501,1301,2005,2405,140
763806335369401428
1,1201,350
505488
1,4301,450
781797
2,9302,870
695710686725
1,5001,540
445454
1,6301,5407,1106,8401,8201,7803,2703,230
Maximum peak discharge
of record (cubic feet per second)
240
505
128
151
4,700
2,260
913
1,820
430
1,170
879
8,000
720
190
407
790
735
1,600
530
5,200
689
421
1,520
630
1,380
9,000
1,750
3,160
Basin, Climatic, and Flood Characteristics 111
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Stationnumber
08248500
08252500
08253000
08253500
08255000
08263000
08264000
08264500
08267500
08271000
08281200
08284000
08295200
08302200
08316000
08321900
08377900
08378500
08397400
09110500
09111500
09112000
09112500
09113300
09113500
09114500
09115500
09118000
09119000
09122000
09122500
Station name
San Antonio River at mouth,near Manassa, Colo.Costilla Creek above Costilla Dam,N. Hex.
Casias Creek near Costilla, N. Mex.
Santistevan Creek near Costilla,N. Mex.
Ute Creek near Amalia, N. Mex.
Latir Creek near Cerro, N. Mex.
Red River near Red River, N. Mex.
Red River below ZW DS nearRed River, N. Mex.Rio Hondo near Valdez, N. Mex.
Rio Lucero near Arroyo Seco,N. Mex.
Wolf Creek near Chama, N. Mex.
Rito de Tierra Amarilla atTierra Amarilla, N. Mex.
Rio en Medio near Santa Fe,N. Mex.
North Fork Tesuque Creek nearSanta Fe, N. Mex.
Santa Fe River near Santa Fe,N. Mex.
Rio de las Vacas near Senorita,N. Mex.
Rio Mora near Terrero, N. Mex.
Pecos River near Pecos, N. Mex.
Hyatt Canyon near Cloudcroft,N. Mex.
East River near Crested Butte,Colo.Slate River near Crested Butte,Colo.Cement Creek near Crested Butte,Colo.
East River at Almont, Colo.
Ohio River at Baldwin, Colo.
Ohio Creek near Baldwin, Colo.
Sunnison River near Gunnison,Colo.Tomichi Creek at Sargents, Colo.
Quartz Creek near Ohio City,Colo.Tomichi Creek at Gunnison, Colo.
Cebolla Creek at Powderhorn,Colo.
Soap Creek near Sapinero, Colo.
Floodregion
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude, in decimaldegrees
37
36
36
36
36
36
36
36
36
36
36
36
35
35
35
35
35
35
32
38
38
38
38
38
38
38
38
38
38
38
38
.177
.898
.897
.884
.953
.829
.622
.674
.542
.508
.956
.699
.792
.770
.687
.993
.777
.708
.933
.864
.866
.824
.664
.766
.702
.542
.395
.560
.522
.291
.561
Longi
tude , in decimaldegrees
105.
105.
105,
105.
105.
105.
105.
105.
105.
105
106
106.
105,
105,
105,
106,
105
105,
105,
106,
106,
106.
106
107
106,
106,
106,
106.
106.
1J7.
107,
877
254
260
281
410
547
,389
,381
,556
,530
,536
,557
,794
.809
.'843
,796
.657
.682
.633
.909
.967
,852
.847
,058
,998
.949
.422
,636
,940
114
316
System
atic Drainage years area, in of square
record miles
59
48
49
49
10
32
24
10
52
58
13
24
20
11
14
30
23
64
16
12
12
12
56
12
26
58
41
24
48
18
11
348
25
16
2
12
10
19
25
36
16
27
49
0
1
18
26
53
189
3
90
70
26
289
47
121
1,012
149
106
1,061
340
57
.00
.10
.60
.15
.00
.50
.10
.70
.20
.60
.70
.70
.63
.60
.20
.80
.20
.00
.08
.30
.10
.10
.00
.20
.00
.00
.00
.00
.00
.00
.40
Mean basin eleva
tion, in
feet
9,100
11,430
11,100
10,500
10,700
11,500
10,790
10,530
10,100
10,790
9,600
8,850
11,300
11,000
9,970
9,470
10,260
9,910
8,320
10,900
10,400
10,900
10,200
10,200
10,000
9,900
10,100
10,700
9,600
10,500
9,900
Mean Mean annual annual precipi- evapor- tation, ation,
in ininches
12.
25.
25.
26.
26.
24.
25.
25.
23.
24.
27.
20.
27.
26.
23.
24.
29.
24.
23.
39.
33.
32.
31.
32.
22.
28.
23.
25.
19.
19.
29.
0
0
0
0
0
0
0
0
0
0
4
5
0
.0
.0
6
0
0
0
0
.0
0
0
0
0
0
0
0
0
0
0
inches
50.0
42.7
42.7
43.1
46.0
47.1
44.3
44.6
49.3
48.7
35.3
40.1
49.6
50.2
51.8
39.1
44.7
45.4
49.6
35.0
35.0
35.0
37.7
35.0
35.5
40.3
35.0
36.7
40.5
38.9
38.7
112 Methods for Estimating Magnitude snd Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
08248500
08252500
08253000
08253500
08255000
08263000
08264000
08264500
08267500
08271000
08281200
08284000
08295200
08302200
08316000
08321900
08377900
08378500
08397400
09110500
09111500
09112000
09112500
09113300
09113500
09114500
09115500
09118000
09119000
09122000
09122500
Relation characteristicL
0
1
1
1
-
1
0
0
0
1
0
0
0
0
0
0
0
1
1
-
-
0
1
0
0
1
0
0
0
0
0
H
0
1
0
0
-
0
0
0
0
0
0
0
0
0
1
0
0
0
0
-
-
0
0
0
0
0
0
0
1
0
1
D
1
0
1
1
-
1
0
0
1
1
0
1
1
0
0
1
0
0
0
-
-
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
0
0
0
0
0
0
0
0
0
0
u
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
8168156262616299
1104848
1071079697
163163127127558554281281
8899
9494
2592592282306016023737
1,090
691209210
2,2802,280
364365664664
3,9003,900
350352361363777785658663451451
5
1,4401,440
1391411011031313
1807980
16616816016927227319019092089554754414141516
232231407405389397
1,0701,070
5857
1,440
975271279
3,1603,160
524532965965
5,6405,650
547557503515
1,2901,3301,1501,170
613619
10
1,8601,8502252301291331617
229102106208214206229354357232233
1,2101,140
75774619192023
388379504500515532
1,4701,480
7272
1,650
1,150311331
3,7903,780
631650
1,1501,1506,7906,820
677702591624
1,6901,8001,5501,610728743
feet per second) for interval (years)
25
2,3702,360
3974021671761922
292132140263276267315467474286289
1,6501,4801,0601,030
25262935
695645625617697727
2,0902,100
9292
1,910
1,370361407
4,6504,620
768806
1,3701,3808,2308,280
840897697773
2,2602,5002,1202,220
881914
50
2,7402,730
5885871952102126
339156169305325315384558568326331
2,0201,7401,3001,240
30313645
1,030913711700848885
2,6402,640
107108
2,110
1,140396465
5,3205,260
870924
1,5201,5409,2909,350
9581,040
771888
2,7303,0802,5902,7201,0001,050
100
3,0803,070
8548382232432330
385180197348375363452653665365372
2,4402,0301,5501,460
35374556
1,4901,260795781
1,0101,0503,2703,250
123124
2,300
1,700431525
6,0305,940
9721,0401,6701,710
10,30010,4001,0701,190
8431,0003,2503,7103,1103,2501,1301,190
Maximum peak discharge
of record (cubic feet per second)
2,620
3,870
181
18
88
126
264
216
541
310
1,900
1,000
20
33
1,500
530
820
4,500
86
1,270
1,240
358
6,500
683
1,260
11,400
804
640
4,620
2,150
1,000
Basin, Climatic, and Flood Characteristics 113
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09124500
09125000
09126000
09127500
09130600
09132900
09140700
09143000
09145000
09146000
09146400
09146500
09146600
09147100
09165000
09172000
09175000
09177500
09188500
09189500
09196500
09198500
09199500
09203000
09204000
09204700
09205500
09208000
09212500
09217900
09218500
Station name
Lake Fork at Gateview, Colo.
Curecanti Creek near Sapinero,Colo.Cimarron River near Cimarron,Colo.Crystal Creek near Maher, Colo.
West Muddy Creek near RaggedMountain, Colo.
West Hubbard Creek near Faonia,Colo.Cottonwood Creek near GrandMesa, Colo.Surface Creek near Cedaredge,Colo.
Uncompahgre River at Ouray,Colo.
Uncompahgre River below Ouray,Colo.
West Fork Dallas Creek nearRidgway, Colo.East Fork Dallas Creek nearRidgway, Colo.Pleasant Valley Creek nearNoel, Colo.
Cow Creek near Ridgway, Colo.
Dolores River below Rico, Colo.
Fall Creek near Fall Creek, Colo.
West Naturita Creek near Norwood,Colo.
lay lor Creek near Gateway, Colo.
Green River at Warren Branchnear Daniel, Wyo.
Horse Creek at Sherman RangerStation, Wyo.
Pine Creek above Fremont Lake,Wyo.Pole Creek below Half Moon Lakenear Finedale, Wyo.
Fall Creek near Pinedale, Wyo.
East Fork River near Big Sandy,Wyo.Silver Creek near Big Sandy, Wyo.
Sand Springs Draw Tributarynear Boulder, Wyo.North Piney Creek near Mason, Wyo.
La Barge Creek near La Barge MOWSRanger Station, Wyo.Big Sandy River at Lechie Ranchnear Big Sandy, Wyo.Blacks Fork near Robertson, Wyo.
Blacks Fork near Millburne, Wyo.
Flood region
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude, in decimal degrees
38
38
38
38
39
39
38
38
38
38
38
38
38
38
37
37
37
38
43
42,
43.
42,
42,
42,
42,
42.
42.
42.
42.
40.
41.
.299
.488
.262
.552
.131
.032
.927
.985
.019
.031
.074
.093
.146
.149
.639
.958
.976
.519
.019
.944
.031
.883
,856
667
750
585
658
508
571
965
032
Longi
tude, in decimal degrees
107
107
107
107
107
107
107
107
107
107
107
107
107
107
108
108
108
109
110
110
109
.229
.414
.544
.506
.575
.613
.950
.854
.676
.674
.851
.813
.919
.644
.060
.005
.327
.109
.117
.389
.769
109.717
109.720
109.
109.
109.
110.
110.
109.
110.
110.
,417
517
623
342
669
283
577
579
System
atic Drainage years area, in of square
record miles
49
27
15
21
10
13
11
47
14
16
15
16
12
18
35
18
12
23
55
20
32
33
33
48
30
18
43
33
47
22
31
334.00
35.00
66.60
42.20
7.42
2.34
2.15
27.40
42.00
75.20
14.10
16.80
7.98
45.40
105.00
33.40
53.00
15.40
468.00
43.00
75.80
87.50
37.20
79.20
45.40
2.77
58.00
6.30
94.00
130.00
152.00
Mean basin eleva
tion, in
feet
10,900
9,700
10,900
9,600
9,400
10,300
9,200
9,700
11,400
11,300
10,200
10,800
9,100
10,700
10,600
10,000
8,500
9,000
9,320
8,880
10,200
11,000
9,460
9,580
9,750
7,300
8,920
8,970
9,250
10,640
10,270
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
24.0
22.0
31.0
25.0
38.0
38.0
23.0
36.0
30.0
32.0
35.0
32.0
20.0
29.0
31.0
32.0
31.0
17.0
22.0
20.0
23.0
22.0
20.0
22.0
20.0
10.0
18.0
25.0
20.0
20.0
19.0
39.5
40.2
39.3
40.1
40.0
39.7
39.9
39.5
35.1
35.3
38.1
38.2
39.9
38.8
35.2
38.4
42.1
44.6
36.6
37.2
35.0
35.7
35.9
37.0
36.0
39.0
38.8
38.0
37.4
34.5
34.6
114 Methods for Estimating Magnitude and Frequancy of Floods in the Southwestarn United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09124500
09125000
09126000
09127500
09130600
09132900
09140700
09143000
09145000
09146000
09146400
09146500
09146600
09147100
09165000
09172000
09175000
09177500
09188500
09189500
09196500
09198500
09199500
09203000
09204000
09204700
09205500
09208000
09212500
09217900
09218500
Relation characteristic L H D 0 U
0
0
0
1
0
0
1
1
0
0
0
0
0
0
1
0
1
0
1
0
0
0
0
0
1
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
1,6801,680252252826824282282858646462424
296296966960
1,4401,430
8182
173173150149640638
1,2701,270
198199384386111111
2,8802,8801,0901,0801,7201,710
937935425424
1,2901,290
7257221010
396395129129928926
1,6401,6301,4601,460
5
2,2002,200
350350
1,1801,170
40740915816061613434
429430
1,3601,3301,9201,890
126132230233282273894884
1,6901,680
392396598604264261
3,6203,6101,3901,3602,0302,0101,1301,120
550546
1,5701,560
8808702727
523522164163
1,2201,2102,1302,1001,8301,810
10
2,5202,530
410412
1,4301,400
48649221821971734041
526528
1,6501,5702,2202,140
159174266274388362
1,0701,0501,9601,940
575578753765407395
4,1004,0901,5901,5202,2202,1701,2401,230
622615
1,7201,700
9709504645
602601185183
1,4101,4002,4202,3502,0702,040
feet per : interval
25
2,9002,930
483491
1,7701,700
58259930730084894752
656659
2,0501,8702,5902,430
206237307326543479
1,3001,2502,2702,240
882867963978636598
4,6804,6601,8401,7102,4502,3501,3601,350
703693
1,8801,8401,0701,040
8176
698700209206
1,6401,6202,7602,6302,3802,320
second) for (years)
50
3,1603,210
534550
2,0501,930
65167938436694
1015260
759762
2,3602,0902,8602,640
244287336366671569
1,4801,4102,4902,4501,1701,1201,1301,140
842773
5,1105,0902,0401,8502,6102,4801,4401,430
757748
1,9801,9301,1501,110
115106766773225223
1,8001,7702,9902,8202,6002,530
100
3,4203,500
583608
2,3302,160
7177584694331041145768
868870
2,6902,3203,1202,840
284338364407810662
1,6701,5702,7002,6501,5301,4201,3001,3101,080
9675,5405,5302,2301,9902,7702,6101,5101,510
807801
2,0702,0201,2101,170
157140831844241240
1,9601,9203,2003,0002,8202,730
Maximum peak discharge
of record (cubic feet per second)
2,720
480
1,790
542
260
93
38
824
2,000
2,400
200
297
500
1,360
2,170
1,390
943
555
5,490
1,860
2,550
1,300
707
2,330
1,030
82
747
196
2,030
2,480
2,530
Basin, Climatic, and Flood Characteristics 115
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09220000
09220500
09223000
09226000
09226500
09227500
09228500
09235600
09244500
09251800
09253400
09264000
09264500
09268000
09268500
09268900
09269000
09273000
09275000
09276000
09277800
09278000
09278500
09280400
09287000
09289500
09302450
09302500
09303300
09303320
09303400
Station name
East Fort of Smith Fork nearRobertson, Wyo.
West Fork of Smith Fork nearRobertson, Wyo.Hams Fork below Pole Creek nearFrontier, Wyo.
Henrys Fork near Lonetree, Wyo.
Middle Fork Beaver Creek nearLonetree, Wyo.
West Fork Beaver Creek nearLonetree, Wyo.
Burnt Fork near Burntfork, Wyo.
Pot Creek above Diversions, nearVernal, UtahElihead Creek near Clark, Colo.
North Fork Little Snake River nearEnc ampment , Wyo .
Battle Creek near Encampment, Wyo.
Ashley Creek below Trout Creeknear Vernal, UtahSouth Fork Asheley Creeknear Vernal, UtahDry Fork above Sinks, near DryFork, Utah
North Fork of Dry Fork nearDry Fork, Utah
Brownie Canyton above Sinks,near Dry Fork, UtahEast Fork of Dry Fork nearDry Fork, UtahDuchesne River at ProvoRiver Trail, near Hanna, Utah
West Fork Duchesne River,Dry Hollow near Hanna, UtahWolf Creek above Rhodes Canyon,near Hanna, Utah
Rock Creek above South Forknear Hanna, UtahSouth Fork Rock Creek near Hanna,Utah
Rock Creek near Hanna, Utah
Hobble Creek at Daniels Summitnear Wallsburg, UtahCurrant Creek Below Red LegHollow, near Fruitland, UtahLake Fork River above Moon Lakenear Mountain Home, UtahLost Creek near Buford, Colo.
Marvine Creek near Buford, Colo.
South Fork White River atBudges Resort, Colo.Wagonwheel Creek at Budges Resort,Colo.
South Fork White River nearBudges Resort, Colo.
Flood region
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude, in decimal degrees
41.
41.
42.
41.
40.
40.
40.
40.
40.
41.
41,
40.
40.
40.
40.
40.
40.
40,
40.
40.
40.
40.
40.
40.
40
40.
40
40.
39.
39.
39.
054
022
111
006
944
947
946
768
.732
050
.133
733
.733
,626
,643
,659
.650
,625
.449
.471
.557
.548
.546
.298
.324
.607
.050
.038
.843
.843
.864
Longi
tude, in decimal degrees
110
110
110
110
110
110
110
109
107
106
107
109
109
109
109
109
109
110
110
110
110
110
110
111
111
110
107
107
107
107
107
.398
.479
.709
.270
.179
.217
.066
.318
.169
.958
.064
.678
.703
.819
.810
.750
.761
.889
.975
.918
.697
.694
.656
.264
.045
.526
.468
.487
.334
.336
.533
System
atic Drainage years area, in of square
record miles
40
42
34
30
22
14
32
28
15
10
10
11
12
37
41
26
18
21
26
38
19
32
32
21
32
38
22
12
11
11
11
53.00
37.20
128.00
56.00
28.00
23.00
52.80
25.00
45.40
9.64
12.80
27.00
20.00
44.40
8.62
8.24
12.00
39.00
43.80
10.60
98.90
15.70
122.00
2.89
50.10
77.90
21.50
59.70
52.30
7.36
128.00
Mean basin eleva
tion, in
feet
10,250
9,790
8,380
10,270
10,480
10,490
10,300
8,167
8,600
9,470
9,590
9,930
10,480
10,240
10,122
10,107
9,360
9,730
9,100
9,040
10,360
10,000
10,200
9,060
8,880
10,800
8,960
9,780
10,569
10,640
10,250
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
20.0
20.0
25.0
23.0
30.5
32.0
29.3
19.6
27.0
30.0
40.0
28.0
30.3
29.7
29.6
28.0
28.6
35.9
28.5
26.6
35.5
30.8
32.9
29.3
27.8
35.4
27.5
32.2
40.0
40.0
40.0
34.7
35.0
38.1
34.7
34.2
35.0
34.3
34.5
40.1
39.8
40.0
34.4
34.8
34.6
34.6
34.3
34.2
35.0
35.0
35.0
35.0
35.0
35.0
34.8
35.0
35.0
40.0
40.0
40.0
40.0
40.0
116 Methods for Estimating Magnitude and Frequency of Flooda in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09220000
09220500
09223000
09226000
09226500
09227500
09228500
09235600
09244500
09251800
09253400
09264000
09264500
09268000
09268500
09268900
09269000
09273000
09275000
09276000
09277800
09278000
09278500
09280400
09287000
09289500
09302450
09302500
09303300
09303320
09303400
Relation characteristicL
0
0
1
0
1
1
1
1
0
0
0
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
0
1
1
0
H
0
1
1
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
1
0
0
D
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
u
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic
2
5015004394388758755775763153151681692812827474
6486453683643353334324293123115255248080
1961951351356956934754744949
1,7201,710
100100
1,7901,790
7272
278279
1,3001,300
595592315319
1,2001,190
189188
2,1002,090
5
743738703698
1,1901,190
8968894804792532595045071421448988844674504594505625524144097447421181192862831791808828766686666971
2,1202,100
142144
2,1602,150
9796
442445
1,7001,690
754742400421
1,6501,610264260
3,1103,050
10
929917910895
1,3901,3901,1501,130
603598316329713717202207
1,0501,020
5304935465246406214764688898831451473483402082119969837867818590
2,3602,310
171177
2,3702,350
114112567574
1,9701,950
847820450504
1,9701,880
312304
3,7903,620
feet per second) for interval (years)
25
1,2001,1701,2101,1701,6601,6701,5301,480772758404429
1,0701,070
295304
1,2301,170
608542662617731703550539
1,0701,060
181185428411243252
1,1301,110
926919108118
2,6502,560
208223
2,6102,570
135132746759
2,3102,270
95390S507625
2,4002,190
373357
4,6704,280
50
1,4201,3801,4601,4001,8601,8701,8501,760
908884476509
1,4101,380
377388
1,3601,290
665578754687794763601592
1,2001,180
210216489464270285
1,2301,2101,0201,010
127142
2,8502,740
235257
2,7702,730
151148893908
2,5702,5001,030
966547721
2,7502,440
418395
5,3204,730
100
1,6601,6001,7301,640.2,0702,0902,2102,0801,0501,010
553592
1,8301,770472483
1,4801,390
721614849758854824650644
1,3401,320
240248551517296318
1,3201,2901,1101,110
148169
3,0502,920
263294
2,9202,880
167163
1,0501,0702,8302,7401,0901,020585817
3,1102,680
462433
5,9805,170
Maximum peak discharge
of record (cubic feet per second)
1,450
2,100
2,230
2,010
775
417
3,200
286
1,060
548
670
630
460
1,010
249
425
240
1,180
740
181
2,760
216
2,710
145
946
2,700
944
442
2,750
336
3,770
Basin, Climatic, and Flood Characteristics 117
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09310500
09329050
09338000
09338500
09339900
09340000
09340500
09341500
09342000
09343000
09344000
09344300
09347500
09352500
09352900
09353500
09357500
09359000
09359500
09365500
09369500
09383400
09383600
09419610
09419623
09442650
09444100
09489070
09489080
09489200
Flood Station name region
Fish Creek above reservoir,near Scofield, UtahSeven Mile Creek near Fish Lake,Utah
East Fork Boulder Creek nearBoulder, Utah
East Fork Deer Creek near Boulder,UtahEast Fork San Juan River above SandCreek, near Pagosa Springs, Colo.East Fork San Juan River nearFagosa Springs, Colo.
West Fork San Juan River aboveBoms Lake, near Fagosa Springs,Colo.
West Fork San Juan River nearFagosa Springs, Colo.
Turkey Creek near Fagosa Springs,Colo.
Rio Blanco near Fagosa Springs,Colo.Navajo River at Banded Peak Ranch,near Chromo, Colo.Navajo River above Chromo, Colo.
Piedra River at BR Ranger Station,near Pagosa Spring, Colo.Los Pinos River near Snows lide Canyonnear Weminuche, Colo.
Valleoito Creek near Bayfield,Colo.
Los Pinos River near Bayfield,Colo.
Animas River at Howardsville,Colo.
Mineral Creek near Silverton,Colo.
Animas River above Tacoma,Colo.La Plata River at Hesperus, Colo.
Middle Mancos River near Mancos ,Colo.
Little Colorado River atGreer, Ariz.Fish Creek near Eagar, Ariz.
Lee Canyon near Charleston Park,Nev.
Deer Creek near Charleston ParkNev.
Romero Creek near Arizona StateLine near Luna, N. Mex.
Campbell Blue Creek near Alpine,Ariz. (USFS)North Fork of East Fork Black Rivernear Alpine, Ariz.Hannagan Creek near Hannagan Meadow,Ariz.Pacheta Creek near Maverick, Ariz.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude, in decimal degrees
39
38
38
38
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
34
34
36
36
33
33
33
33
33
.774
.628
.042
.001
.390
.369
.486
.379
.369
.213
.085
.032
.429
.639
.477
.383
.833
.797
.570
.290
.374
.017
.076
.340
.312
.950
.746
.903
.647
.740
Longi
tude, in decimal degrees
111.190
111.647
111.449
111.389
106.841
106.892
106.930
106.899
106.940
106.794
106.689
106.732
107.193
107.333
107.543
107.577
107.599
107.695
107.780
108.040
108.230
109.457
109.462
115.650
115.619
108.983
109.205
109.322
109.289
109.540
System
atic Drainage years area, in of square
record miles
49
22
20
20
30
46
17
28
13
37
41
14
14
13
24
13
47
14
11
72
15
23
13
26
15
19
28
13
13
23
60
24
21
1
64
86
41
87.
23
58
69
96,
82
25,
72,
270,
55,
43
348,
37,
12.
30.
15.
9.
1.
10.
11.
38.
1.
14.
.10
.00
.40
.90
.10
.90
.20
.90
.00
.00
.80
.40
.30
.30
.10
.00
.90
.90
.00
.00
.10
,90
.90
20
27
80
60
10
61
80
Mean basin eleva
tion, in
feet
8,710
10,025
10,500
9,290
10,400
10,200
10,700
10,000
10,000
10,000
10,500
10,000
10,300
11,200
11,400
10,400
11,900
11,700
11,200
10,200
9,300
9,400
9,160
9,350
9,650
9,000
8,300
9,060
9,160
8,810
Mean annual precipi tation,
in inches
29.4
27.0
28.8
20.7
42.0
39.0
43.0
42.0
39.0
39.0
37.0
37.0
38.0
45.0
46.0
37.0
31.0
38.0
34.0
35.0
28.0
31.2
26.1
19.5
17.1
19.0
20.0
27.5
30.0
30.3
Mean annual
- evapor
ation, in
inches
37.3
39.2
39.7
40.0
36.0
36.8
34.6
36.6
37.3
36.7
35.0
36.5
37.4
34.9
34.5
36.5
35.0
35.0
34.9
40.5
42.8
43.8
45.2
64.9
65.2
41.5
40.1
41.1
41.3
39.7
118 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09310500
09329050
09338000
09338500
09339900
09340000
09340500
09341500
09342000
09343000
09344000
09344300
09347500
09352500
09352900
09353500
09357500
09359000
09359500
09365500
09369500
09383400
09383600
09419610
09419623
09442650
09444100
09489070
09489080
09489200
Relation characteristic L H D 0 U
1
1
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
1
-
0
1
1
1
-
1
-
-
1
0
0
0
1
c
0
0
0
0
1
0
0
0
0
-
0
0
0
0
0
-
0
0
0
0
-
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
-
0
0
1
0
-
0
-
-
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
1
0
-
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
1
0
1
1
0
Peak discharge (cubic indicated recurrence
2
5955951801801991992020665666922922733732
1,3101,310
335335851851649650716720876877322324
1,1402,3102,310
979977827824
5,3705,330
450450
1241741757374111144
644343
318
25105105
5
8288272432453033046463
1,0101,0101,3501,350
978974
1,8301,820
521519
1,2001,200
897900984
1,0001,2701,270
517521
1,4503,2503,2501,2701,2601,1001,0907,3007,110
756755
19631632015816185861616
116113113
486
42179181
10
985983284291375376122117
1,2701,2701,6401,6401,1401,1302,1802,160
659650
1,4501,4401,0701,0801,1701,2101,5601,550659662
1,6203,8603,8501,4601,4501,3001,2708,5408,070
986981
2474274352302352492443232
156195194
598
54235239
feet per interval
25
1,1901,190
335353467470248227
1,6301,6202,0202,0101,3501,3202,6302,580
849820
1,7801,7501,2901,3001,4201,5001,9401,910
849842
1,8404,6104,5501,6901,6601,5601,490
10,1009,1201,3001,290
3125865973363407697186662
209357347
741
70313320
second) for (years)
50
1,3401,340
371400536540399352
1,9301,9102,3202,3001,5101,4702,9702,8901,000
9482,0402,0001,4601,4801,6201,7202,2502,190
999977
2,0105,1705,0601,8601,8201,7601,650
11,1009,7401,5601,540
360715725423423
1,5801,420
10594
249535507
848
82376385
100
1,5001,490
408449606611615523
2,2502,2002,6202,5901,6701,6103,3203,2001,1601,0802,3102,2401,6301,6501,8301,9502,5602,4601,1501,110
2,1705,7105,5502,0201,9701,9801,830
12,20010,4001,8201,780
407854859518508
3,0202,640
158135
289778718
951
94442451
Maximum peak discharge
of record (cubic feet per second)
1,450
369
483
350
2,260
2,460
1,290
2,330
860
2,500
1,480
1,400
1,800
650
7,050
13,800
1,980
1,700
9,500
1,880
297
615
236
880
50
480
619
1,070
70
323
Basin, Climatic, and Flood Characteristics 119
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES- -Continued
Stationnumber
09490800
09491000
10011500
10012000
10153500
10154000
10183900
10205100
10205200
10205300
10241430
10284800
13011500
13011800
13011900
13012000
13014500
13019210
13019220
13019400
13021000
13022550
13023000
13023800
13038900
13050700
13117200
13117300
13120000
13120500
13128900
Station name
North Fork White River near Greer,Ariz.North Fork White River near McNary,Ariz.Bear River near Utah-WyomingState Line
Mill Creek at Utah-WyomingState Line
Prove River near Kamas, Utah
Shingle Creek near Kamas, Utah
East Fork Sevier River nearRubys Inn, UtahSheep Creek near Salina, Utah
West Fork Sheep Creek near Salina,Utah
Sheep Creek at Mouth near Salina,Utah
Red Creek near Faragonah, Utah
Inyo Creek near Lone Pine, Calif.
Pacific Creek at Moran, Wyo.
Blackrock Creek Tributarynear Moran, Wyo.Buffalo Fork above Lava Creek,near Moran, Wyo.Buffalo Fork near Moran, Wyo.
Gros Ventre River at Kelly,Wyo.
Rim Draw near Bondurant, Wyo.
Sour Moose Creek nearBondurant, Wyo.
Cliff Creek near Bondurant, Wyo.
Cabin Creek near Jackson, Wyo.
Red Creek near Alpine, Wyo.
Greys River above Reservoir,near Alpine, IdahoFish Creek near Smoot, Wyo.
Targhee Creek near Macks Inn,Idaho
Mail Cabin Creek near Victor,Idaho
Main Fork near Goldburg, Idaho
Sawmill Creek near Goldburg, Idaho
Big Lost River at Wild Horse, nearChilly, Idaho
Big Lost River at Howell Ranch,near Chilly, IdahoLower Cedar Creek above diversions,near Mackay, Idaho
Floodregion
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Lati
tude, in decimaldegrees
34.
34.
40.
40.
40.
40.
37.
38.
38.
38,
37.
36.
43.
43.
43.
43.
43,
43,
43,
43.
43.
43.
43.
42.
44.
43.
44.
44.
43.
43.
43.
014
046
965
992
583
612
576
778
789
800
857
597
851
,786
,837
.836
,622
,133
150
228
.249
194
143
519
647
497
402
311
933
998
966
Longi
tude, in decimaldegrees
109.
109.
110.
110.
111.
111.
112.
111.
111.
Ill,
112,
118,
110,
110.
110.
110.
110,
110,
110,
110.
110.
110.
110.
110.
111.
110.
113.
113.
114.
114.
113.
642
737
853
842
008
116
,265
,680
,688
.683
.675
.182
.516
,142
,439
,508
,625
,228
256
505
.778
.927
976
896
342
983
405
339
113
020
578
System
atic Drainage years area, in of square
record
13
39
44
19
20
10
25
12
12
12
11
11
40
11
21
16
14
11
18
11
12
10
35
11
18
10
10
13
43
78
16
miles
40
78
172
59
29
8
71
0
0
1
6
1
169
0
323
378
622
3
2
58
8
3
448
3
20
3
15
74
114
450
8
.20
.20
.00
.00
.60
.40
.60
.30
.43
.47
.30
.54
.00
.80
.00
.00
.00
.41
.77
.60
.71
.88
.00
.60
.80
.27
.60
.30
.00
.00
.26
Mean basin eleva
tion, in
feet
9
9
9
9
9
9
8
9
8
8
9
8
8
9
9
8
8
8
7
8
7
7
8
7
8
8
8
8
8
8
9
,520
,320
,770
,320
,710
,280
,640
,670
,690
,780
,050
,000
,160
,240
,270
,850
,850
,200
,760
,200
,300
,890
,080
,600
,300
,400
,730
,390
,540
,590
,900
Mean Mean annual annual precipi- evapor- tation, ation,
in ininches
34.
32.
31,
24
33,
30,
21,
23,
23,
22
21,
20
30,
27,
41,
31
38,
16
16,
25,
25.
25.
40,
24,
27.
23.
38.
35.
39.
38.
30.
.2
,2
,7
.0
7
,2
,7
.0
.0
.5
,0
,0
.0
.0
.0
.5
,0
.0
,0
.0
.0
,0
.0
,0
0
0
,0
.0
.0
0
0
inches
42.6
43.3
34.6
34.6
35.0
35.0
38.7
39.8
39.8
39.7
39.7
76.1
35.0
32.7
34.7
35.0
34.6
36.0
35.9
35.5
35.0
35.3
35.3
37.2
35.1
37.6
30.3
35.6
30.1
30.1
32.4
120 Methods for Estimating Msgnitude snd Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09490800
09491000
10011500
10012000
10153500
10154000
10183900
10205100
10205200
10205300
10241430
10284800
13011500
13011800
13011900
13012000
13014500
13019210
13019220
13019400
13021000
13022550
13023000
13023800
13038900
13050700
13117200
13117300
13120000
13120500
13128900
Relation characteristic L H D 0 U
.
0
0
0
1
0
0
0
0
0
1
0
1
0
0
0
0
1
1
0
0
-
1-
0
0
1
1
0
0
1
.0
0
0
0
0
0
0
0
0
1
0
1
0
0
1
1
0
0
0
0
-
0
-
0
1
0
0
0
0
0
.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
-
0
-
0
0
0
0
1
1
0
.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
-
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
....
455404405
1,8801,880
387387503502178177112114
4433
1212151577
2,4802,480
4242
4,2604,2504,0604,0503,2003,220
14141515
600597127126
403,4203,420
362562553737
137139374379753755
2,1702,170
181180
5
....
648740745
2,4102,400
543545633629203200196206
9988
232424272121
3,1303,110
6360
5,0805,0604,6504,6103,9804,090
16172020
832821163162
_--_
694,5204,540
623263255151
193202522548
1,0201,0303,0103,030
227224
10
....
7691,0301,0402,7202,710
64665271170421821626729313131313333431403636
3,5403,490
7873
5,6005,5505,0004,9304,5104,760
17212425
994969184183
915,2305,260
823703706062
230251619680
1,2001,2203,5003,540
257252
feet per second) for interval (years)
25
....
9221,4801,4803,0803,060
77679480479523523837743319192020474842626361
4,0503,960
10088
6,2406,1405,4205,3405,2005,660
18292832
1,2101,160
208210
1196,1306,170
1084244287378
278319741864
1,4101,4604,0704,140
294287
50
....
1,0401,8901,8703,3403,310
87290286886024725847555525242726596052819083
4,4204,290
118101
6,7106,5805,7105,6505,7306,350
19363139
1,3701,310
224232
1406,7906,830
1284624738391
313372832
1,0101,5701,6404,4604,570
321315
100
....
1,1502,3502,3003,5803,550
9671,010
93092525827858869133303433727262
102123108
4,7804,620
137114
7,1707,0005,9805,9506,2707,040
20453445
1,5501,460239254
1617,4507,480
14849951793
105349424922
1,1501,7201,8104,8104,950
349343
Maximum peak discharge
of record (cubic feet per second)
510
2,310
3,230
690
825
238
448
17
12
32
48
42
5,350
110
6,540
5,960
6,960
18
26
1,150
167
44
7,230
81
458
81
273
651
1,440
4,420
310
Basin, Climatic, and Flood Characteristics 121
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
13135200
13135800
10313000
10315000
10315500
10315800
10353600
10316500
10317400
10317430
10317500
10319000
10319470
10319500
10320500
10322000
10322980
10323000
10323200
10323870
10324500
10327600
10328000
10328240
10329000
10329500
10330300
10332200
10336030
10336080
10352500
Station name
Prairie Creek near Ketchum, Idaho
Adams Gulch near Ketchum,Idaho
Starr Creek near Deeth, Nev.
Marys River near Deeth, Nev.
Marys River above Hot SpringCreek near Deeth, Nev.
Humboldt River Tributary nearHalleck, Nev.
Secret Creek Tributary nearArthur , Nev .Lamoille Creek near Lamoille,Nev.North Fork Humboldt River nearNorth Fork, Nev.Jim Creek near Tuscarora, Nev.
North Fork Humboldt River atDevils Gate near Halleck, Nev.
South Fork Homboldt Rivernear Lee, Nev.
Willow Creek Tributary nearJiggs, Nev.
Huntington Creek Tributary nearLee, Nev.South Fork Humboldt River nearElko, Nev.
Maggie Creek at Carlin, Nev.
Cole Creek near Palisade, Nev.
Pine Creek near Palisade,Nev.
Bob Creek near Beowawe, Nev.
Willow Creek above Willow CreekReservoir near Tuscarora, Nev.Rock Creek near Battle Mountain,Nev.Humboldt River Tributary nearGolconda, Nev.Pole Creek near Golconda, Nev.
Humboldt River Tributary nearBliss, Nev.
Little Humboldt River nearParadise Valley, Nev.
Martin Creek near ParadiseValley, Nev.Mullinex Creek near ParadiseValley, Nev.
Raspberry Creek near Mill City,Nev.Toulon Drain Tributary nearLovelock, Nev.
Humboldt Slough Tributary nearBradys Hot Spring, Nev.
McDermitt Creek near McDermitt,Nev.
Flood region
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Lati
tude , in decimal degrees
43
43
41
41
41
40
40
40
41
41
41
40
40
40
40
40
40
40
40
41
40
41
40
40
41
41
41
40
40
39
41
.817
.706
.017
.317
.253
.969
.867
.691
.575
.297
.181
.567
.513
.562
.724
.719
.585
.596
.660
.217
.825
.011
.914
.999
.415
.533
.511
.787
.108
.851
.967
Longi
tude , in decimal degrees
114.597
114.397
115.267
115.267
115.256
115.447
115.261
115.476
115.911
115.787
115.493
115.550
115.662
115.717
115.829
116.094
116.149
116.174
116.408
116.467
116.579
117.356
117.531
117.658
117.373
117.428
117.540
117.998
118.557
118.928
117.834
System
atic Drainage years area, in of square
record miles
10
10
11
17
43
20
13
49
16
16
46
11
22
27
69
11
24
16
18
11
48
17
14
18
36
63
18
19
18
22
38
18
10
50
355
415
3
3
25
11
22
830
500
0
770
1,310
400
11
999
13
81
875
3
10
1
1,030
172
27
9
0
11
225
.00
.90
.60
.00
.00
.00
.00
.00
.00
.90
.00
.00
.82
.00
.00
.00
.40
.00
.90
.00
.00
.40
.70
.90
.00
.00
.30
.38
.80
.00
.00
Mean basin eleva
tion, in
feet
8,420
7,370
6,750
6,880
6,220
5,680
6,950
9,090
7,780
6,560
7,000
8,610
5,600
6,455
6,940
6,120
5,990
7,000
6,050
6,140
5,930
4,960
6,760
4,950
5,520
6,190
6,025
4,970
4,300
4,600
5,875
Mean annual precipi tation,
in inches
43.0
25.0
16.0
15.0
10.0
10.0
14.0
21.0
18.0
16.0
14.0
22.0
10.0
11.6
10.0
11.0
11.0
13.1
10.0
12.0
10.0
8.0
13.4
8.0
8.0
10.8
7.1
7.9
5.0
6.0
11.0
Mean annual evapor
ation, in
inches
30.1
30.1
40.1
39.9
39.9
40.1
40.0
40.0
40.0
40.0
40.0
40.0
40.1
40.1
40.0
40.7
41.8
41.9
42.5
40.1
42.3
44.3
44.2
43.4
41.0
40.1
40.0
41.7
40.0
39.1
40.0
122 Methods for Estimating Msgnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
13135200
13135800
10313000
10315000
10315500
10315800
10315950
10316500
10317400
10317430
10317500
10319000
10319470
10319500
10320500
10322000
10322980
10323000
10323200
10323870
10324500
10327600
10328000
10328240
10329000
10329500
10330300
10332200
10336030
10336080
10352500
Relation characteristic L H D 0 U
0
0
0
0
1
1
-
0
0
1
1
0
-
0
1
0
0
1
1
1
0
-
0
-
1
1
1
-
-
-
0
0
0
0
0
1
0
-
0
0
1
1
0
-
0
0
0
1
0
0
0
0
-
1
-
1
0
0
-
-
-
0
0
1
0
0
0
0
-
0
0
0
0
0
-
0
0
0
0
1
0
0
0
-
0
-
0
0
1
-
-
-
0
0
0
0
0
0
0
-
0
0
0
0
0
-
0
0
0
0
0
0
0
0
-
1
-
1
0
0
-
-
-
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
0
1
0
0
0
1
1
1
0
Peak discharge (cubic indicated recurrence
2
1671693940
1811842833144224341314
-
2942141594934348
624644596566
11299340
1,0101,030
138202
911
1372313436
325323462485
316666
21116161423424248242 -
65--
11_
72564565
5
2442558388
3073184545607387793234
5056355113413388
1011,3501,410
760709
19711838
1,4101,480
3765635459
5458246674
562559
1,3201,380
54226214
36308454
1,1001,100
585554 --
113
19
1271,3401,330
10
296321125134403422571792
1,0201,110
5052
--
62660637160159133157
2,0302,140
861776
261,1001,3601,6801,830
6431,000
136140
1,1301,630
94109746740
2,2402,350
77458404
51534863
1,8901,860
899816
____
161
28
1862,0602,020
feet per second) for interval (years)
25
362409194208535573721
1,1601,4901,660
7880
81786748191193214250
3,1703,350
981875
341,7202,2002,0502,3701,1501,750
361340
2,4603,230
135162
1,0101,0003,8804,040
1041,020
818
67988
1,6403,4203,3001,4001,200
218
38
2543,2203,100
50
412476259271641692832
1,4501,9302,160
104104
95883835214220296334
4,2404,4601,070
960
402,2702,9302,3402,8201,6902,430
670597
4,0804,880
172207
1,2301,2205,4905,660
1241,7701,340
811,5002,4005,1104,8701,8401,540
265
45
3104,2604,050
100
462541337341753815944
1,7402,4602,740
134131
109982925236246401434
5,5105,7401,1501,040
472,9203,7402,6303,2702,4003,2001,160
9926,4407,020
212253
1,4601,4407,4707,590
1462,9602,150
942,2003,3307,3906,9602,3501,920
312
53
3685,4605,140
Maximum peak discharge
of record (cubic feet per second)
293
124
391
616
4,210
99
42
829
170
541
10,400
935
15
2,160
2,830
2,440
1,090
3,140
130
820
4,800
1
4,000
113
2,380
9,000
1,320
25
350
710
3,970
Basin, Climatic, and Flood Characteristics 123
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10353000
10353500
10353520
10353600
10353700
10353710
10353730
10353770
10361700
10366000
10370000
10371000
10371500
10378500
10384000
10390400
10392300
10392800
10393500
10393900
10396000
10397000
10403000
10406500
13155200
13155300
13161100
13161200
13161300
13161500
13161600
Station name
East Fork Quinn River nearMcDermitt, Nev.Quinn River near McDermitt, Nev.
Eagle Creek near Orovada, Nev.
Kings River near Orovada,Nev.Leonard Creek near Denio, Nev.
Black Rock Desert Tributarynear Sulphur, Nev.Dry Creek near Gerlach, Nev.
South Willow Creek nearGerlach, Nev.
Badger Creek Tributary nearVya, Nev.
Twer.'tymile Creek near Adel,Oreg.
Catnas Creek near Lakeview, Oreg.
Drake Creek near Adel, Oreg.
Deep Creek above Adel, Oreg.
Honey Creek near Plush, Oreg.
Chewaucan River near Paisley,Oreg.
Bridge Creek near ThompsonReservoir, Oreg.Silvies River near Senaca, Oreg.
Crowsfoot Creek near Burns, Oreg.
Silvies River near Burns, Oreg.
Devine Canyon near Burns , Oreg .
Donner and Blitzen River nearFrenchglen, Oreg.Bridge Creek near Frenchglen,Oreg.Silver Creek near Riley, Oreg.
Trout Creek near Denio,Nev.
Burns Gulch near Glenns Ferry,Idaho
Lower Canyon Creek at Stout,near Glenns Ferry, IdahoBruneau River near Charleston,Nev.Seventy Six Creek near Charleston,Nev.
Meadow Creek near Rowland, Nev.
Bruneau River at Rowland, Nev.
McDonald Creek near Rowland, Nev.
Flood region
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Lati
tude, in decimal degrees
41.983
41.775
41.651
41.907
41.528
40.900
40.729
41.017
41.722
42.072
42.216
42.200
42.189
42.425
42.685
43.025
44.175
43.899
43.715
43.772
42.791
42.844
43.692
42.156
43.195
43.154
41.514
41.711
41.900
41.933
41.919
System-
Longi- atic Drainage tude.in years area, in decimal of square degrees record miles
117
117
117
118
118
118
119
119
119
119
120
120
120
119
120
121
119
119
119
119
118
118
119
118
115
115
115
115
115
115
115
.583
.804
.778
.308
.712
.628
.452
.350
.372
.962
.101
.011
.001
.922
.569
.200
.214
.497
.176
.004
.867
.849
.658
.458
.333
.309
.451
.482
.678
.674
.772
33
35
23
16
20
14
16
23
17
56
25
26
57
65
72
16
15
14
79
17
60
39
29
65
12
18
15
16
17
31
16
140,
1100.
3.
20.
52,
33.
3
31.
7.
194
63
67
249
170
275
10
18
8
934
4
200
30
228
88
0
14
44
3
57
382
10
.00
.00
.44
.50
.00
.00
.50
.00
.70
.00
.00
.00
.00
.00
.00
.60
.40
.50
.00
.96
.00
.00
.00
.00
.76
.20
.00
.52
.80
.00
.80
Mean basin eleva
tion, in
feet
6,081
5,498
5,600
6,400
6,318
5,125
5,200
5,941
6,156
5,800
6,210
5,880
6,110
5,910
6,050
6,170
5,530
5,790
5,200
5,410
6,160
5,890
5,180
5,920
6,160
5,960
6,620
7,510
6,180
6,790
7,030
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
9.5
9.3
12.0
19.8
10.0
7.2
10.0
8.8
10.0
15.0
20.0
15.0
17.0
20.0
18.0
25.0
30.0
25.0
19.0
15.0
14.0
12.0
20.0
14.0
15.0
15.0
12.9
14.5
10.7
10.6
14.0
40.0
40.0
40.0
40.0
40.0
39.9
43.9
45.1
41.9
41.4
40.2
40.2
40.2
39.9
40.0
38.9
34.8
35.0
35.0
34.8
44.0
44.2
36.1
41.0
39.3
40.0
40.0
40.0
39.8
39.7
39.8
124 Methods for Estimating Msgnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10353000
10353500
10353520
10353600
10353700
10353710
10353730
10353770
10361700
10366000
10370000
10371000
10371500
10378500
10384000
10390400
10392300
10392800
10393500
10393900
10396000
10397000
10403000
10406500
13155200
13155300
13161100
13161200
13161300
13161500
13161600
Relation characteristic L H D 0 U
1
1
-
0
0
-
-
1
1
1
0
0
0
0
1
0
1
0
1
-
0
1
1
1
0
0
1
0
0
1
0
0
0
-
1
0
-
-
0
0
0
1
0
0
0
1
0
0
0
0
-
0
0
0
0
0
1
1
0
0
0
0
1
1
-
0
0
-
-
0
0
1
0
0
0
1
0
0
0
1
0
-
1
0
1
0
0
0
0
0
0
1
0
0
0
-
0
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
425426255300
3246507986
-
158----
3240451417
1,4601,450
472464482474
1,2801,270
465466955952666672744950
1,3401,350
411,3801,370
108109611612119122
66
9393263622231982007847884345
5
658665686826
55122130194210
----
281 --
552072115458
3,0202,960
821796
1,2701,2202,5702,5301,2001,1901,5801,570
1101111051137276
2,2202,240
712,1702,140
174178
1,0201,030
1932031213
1611601251494949
432431
1,2901,310
6369
10
828849
1,1001,410
74212220312339 -
397 -
77489474108111
4,4704,3101,1301,0702,1401,9803,7003,5901,9501,9202,1102,100
1471501271488797
2,9102,970
982,6902,630
221231
1,3101,340
2532761819
2212192973237171
639627
1,6701,710
7689
feet per second) for interval (years)
25
1,0601,1101,7402,360
99394384521554
----
545
1041,2301,110226214
6,8406,4601,6401,5103,7803,3405,4605,2203,2803,1802,9102,880
205208156200106127
3,8804,020
1323,3303,230
281302
1,6901,770
3423892728
315307780738105101959916
2,1802,280
93119
50
1,2401,3202,3103,190
118597551727751
666
1242,2401,920
366327
9,0508,4502,1101,9105,4904,7207,0106,6404,5904,4003,6203,570
256257178241120150
4,6804,900
1573,7803,660
327358
1,9802,110
4204873636
401384
1,4901,290
133125
1,2401,1602,5802,730
105141
100
1,4401,5502,9404,070
137878770985985
790
1453,8603,200
566480
11,70010,8002,6702,3707,7106,4908,7808,2506,1905,8804,4304,360
316312201283134174
5,5505,840
1844,2304,100
373414
2,2702,460
5075934645
502472
2,6902,160
165152
1,5501,4303,0003,200
118163
Maximum peak discharge
of record (cubic feet per second)
1,270
1,580
10
770
612
3,940
736
1,730
230
3,670
3,190
6,210
9,420
11,000
6,490
218
152
88
4,960
28
4,270
301
1,810
470
22
500
1,890
89
940
2,140
85
Baain, Climatic, and Flood Characteriatics 125
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
13162200
13162400
13162500
13162600
13169500
13170000
13170100
13172200
13172666
13172668
13172680
13172720
13172735
13172740
13172800
13175900
13176600
13176900
13177000
13177200
13177800
13178000
13182100
13182150
13184200
13184800
13185000
13185500
13186000
13186500
13187000
Flood Station name region
Jarbidge River at Jarbidge, Nev.
Buck Creek near Jarbidge, Nev.
East Fork Jarbidge River nearThree Creek, Idaho
Columbet Creek near Jarbidge, Nev.
Big Jacks Creek near Bruneau,Idaho
Little Jacks Creek near Bruneau,Idaho
Sugar Creek Tributary near Grasmere,Idaho
Fossil Creek near Oreana, Idaho
West Fork Reynolds Creek nearReynolds , IdahoEast Fork Reynolds Creek nearReynolds , IdahoReynolds Creek at Tollgate Heir,near Reynolds, Idaho
Macks Creek near Reynolds, Idaho
Salmon Creek near Reynolds, Idaho
Reynolds Creek at outlet weir,near Reynolds, Idaho
L Squaw Creek Tributary nearMar sing, IdahoReed Creek near Owyhee, Nev.
Taylor Canyon Tributary nearTuscarora, Nev.
Jack Creek below Schoonover Creek,near Tuscarora, Nev.Jack Creek near Tuscarora, Nev.
South Fork Owyhee River at SpanishRA near Tuscarora, Nev.South Fork Owyhee River nearWhiterock, Nev.Jordan Creek above LN Tree Creek,near Jordan Valley, Or eg.Dago Gulch near Rockville, Oreg.
Long Gulch near Rockville, Oreg.
Roaring River near Rocky Bar,Idaho
Beaver Creek near Lowman, Idaho
Boise River near Twin Springs,Idaho
Cottonwood Creek at ArrowrockReservoir, IdahoSouth Fork Boise River nearFeatherville, Idaho
Lime Creek near Bennett, Idaho
Fall Creek near Anderson Ranch
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Lati
tude , in decimal degrees
41.
41.
42.
41.
42.
42.
42.
43.
43.
43.
43.
43.
43.
43.
43.
41.
41.
41.
41.
41.
41.
42.
43.
43.
43.
43.
43.
43.
43.
43.
43.
862
979
033
967
785
833
564
094
070
070
100
230
270
180
364
896
236
508
500
428
800
874
294
321
706
972
659
632
494
417
433
Longi
tude, in decimal degrees
115
115
115
115
115
116
115
116
116
116
116
116
116
116
116
116
116
116
116
116
116
116
117
117
115,
115.
115.
115.
115,
115.
115.
.428
.432
.372
.485
.983
.000
.907
.449
.760
.750
.770
.790
.790
.760
.921
.061
.036
.072
.100
.178
.483
.953
.254
.195
.464
.608
.726
.824
.306
.267
,386
System
atic Drainage years area, in of square
record miles
15
16
22
16
33
11
19
17
14
16
13
15
15
16
19
17
13
16
13
16
26
24
12
10
17
10
76
11
42
11
12
22.60
20.20
84.60
3.37
253.00
100.00
4.50
19.70
0.20
0.16
21.00
12.30
14.00
90.00
1.81
6.51
1.20
19.80
31.00
330.00
1,080.00
440.00
3.09
1.38
23.30
9.30
830.00
20.90
635.00
131.00
55.30
Mean basin eleva
tion, in
feet
7,950
6,990
7,600
7,020
5,150
5,020
4,860
3,920
6,880
6,800
5,940
4,860
4,870
5,000
4,440
6,400
6,600
7,450
6,890
6,170
6,060
5,780
4,560
5,030
7,200
5,860
6,350
5,180
6,840
6,140
6,070
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
18.4
13.2
19.0
14.2
13.0
12.0
12.0
12.0
41.0
41.0
31.0
19.0
19.0
20.0
13.0
12.0
16.0
14.2
12.0
12.0
9.4
15.0
12.0
12.0
43.0
45.0
42.0
23.0
37.0
23.0
26.0
40.0
40.0
39.8
40.0
39.3
39.5
40.0
43.0
43.0
43.0
43.1
43.7
43.8
43.5
44.1
39.8
40.0
40.0
40.0
40.0
40.0
42.1
43.3
43.6
29.4
30.0
33.8
36.4
35.2
35.7
35.4Dam, Idaho
126 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Ststes
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
13162200
13162400
13162500
13162600
13169500
13170000
13170100
13172200
13172666
13172668
13172680
13172720
13172735
13172740
13172800
13175900
13176600
13176900
13177000
13177200
13177800
13178000
13182100
13182150
13184200
13184800
13185000
13185500
13186000
13186500
13187000
Relation characteristic L H D 0 U
0
1
0
0
1
0
-
1
1
1
1
0
0
0
1
0
1
0
0
0
1
0
-
-
0
0
1
0
1
0
0
0
0
0
0
0
0
-
1
0
0
0
1
1
0
0
0
0
0
0
1
0
1-
-
0
0
1
0
0
0
0
0
0
0
0
1
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
3062958586
4494431213
230243143160
3843475555
20119597968182
4384321313232444
168165200197615627
1,5401,5501,9401,900
29
1633031910299
6,7606,700
9193
4,6204,550
659640509488
5
4774491641676236182427
493531423451
66196196
9966
273264264250213206
1,0901,040
3232495379
239234299295
1,3101,3302,4602,5303,0102,930
51
28453431149143
9,3109,160
191193
5,9705,820
964935706667
10
5975392342367327263439
749834739773
95456432111188
320311451408355332
1,7801,630
525273791014
286279371365
1,9501,9603,1003,2703,7903,640
74
40529490181174
11,00010,700
284284
6,8006,5501,1701,140
849787
25
7566583443418648735058
1,1901,3401,3301,310
1281,1701,010
15141010
380376801675617541
3,0302,610
8783
1091181421
345339468465
2,9702,9203,9504,3504,8704,650
100
53620565223216
13,20012,700
436422
7,7707,4201,4201,4101,040
956
second) for (years)
50
8787514434309589866374
1,6101,8101,9401,810
1552,1901,780
18171111
424429
1,160938887746
4,2803,550
1211121401491727
390386545545
3,9003,7704,6105,2405,7405,480
121
63684623256251
14,90014,300
577542
8,4608,0901,6101,6401,2001,110
100
1,000845558530
1,0501,100
7989
2,1302,3702,7202,410
1823,9203,060
21191313
468483
1,6401,2801,230
9995,8804,730
1631471761842032
434434626629
4,9904,7205,2706,1406,6506,350
143
73745680288286
16,60016,000
745678
9,1208,7501,8001,8701,3601,260
Maximum peak discharge
of record (cubic feet per second)
700
380
798
46
2,100
908
105
2,860
14
11
404
1,200
1,007
3,801
93
95
12
325
465
4,130
3,830
7,530
46
18
575
195
18,800
330
7,960
1,180
1,150
Basin, Climatic, and Flood Characteristics 127
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
13191000
13196500
13200000
13200500
13207000
13207500
13210300
13213900
13214000
13216500
13227000
13228300
14044000
14036800
14037500
14038530
14038550
14038600
14038750
14038900
14039200
14040500
14040700
14040900
14041500
14041900
14042000
14042500
14043800
14043850
14043900
Flood Station name region
South Fork Boise River nearLenox, Idaho
Bannock Creek near Idaho City,Idaho
Mores Creek near Arrowrock Dam,Idaho
Robie Creek near Arrowrock Dam,Idaho
Spring Valley Creek near Eagle,Idaho
Dry Creek near Eagle, Idaho
Bryans Run near Boise, Idaho
Malheur River Tributary nearDrewsey, Oreg.
Malheur River near Drewsey, Oreg.
Near Fork Malheur River above BeulahReservoir, near Beulah, Oreg.Bully Creek near Vale, Oreg.
Lytle Creek near Vale, Oreg.
Lost Valley Creek Tributary nearIronside, Oreg.
John Day River near Prairie City,Oreg.Strawberry Creek above Slide Creek,near Prairie City, Oreg.John Day River near John Day, Oreg.
East Fork Canyon Creek nearCanyon City, Oreg.
Vance Creek near Canyon City, Oreg.
Beech Creek near Fox, Oreg.
Fields Creek near Mount Vernon,Oreg.
Venator Creek near Silvies, Oreg.
John Day River at Picture Gorge,near. Dayville, Oreg.Whisky Creek near Mitchell, Oreg.
Bruin Creek near Dale, Oreg.
North Fork John Day near Dale,Oreg.
Line Creek near Lehman Springs,Oreg.
Camas Creek near Lehman, Oreg.
Camas Creek near Ukiah, Oreg.
Bridge Creek near Prairie City,Oreg.
Cottonwood Creek near Galena,Oreg.Granite Creek near Dale, Oreg.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Lati
tude, in decimal degrees
43
43
43
43
43
43
43
43
43
43
43
43
44
44
44
44
44
44
44
44
43
44
44
44
44
45
45
45
44
44
44
.500
.808
.648
.630
.739
.732
.451
.780
.785
.948
.958
.957
.314
.319
.342
.419
.246
.289
.568
.393
.999
.521
.522
.897
.999
.169
.171
.157
.542
.653
.894
System-
Longi- atic Drainage tude.in years area, in decimal of square degrees record miles
115.683
115.774
115.989
115.999
116.300
116.304
116.069
118.358
118.331
118.173
117.342
117.226
117.903
118.557
118.656
118.903
118.911
118.978
119.108
119.307
119.275
119.625
119.922
118.793
118.940
118.711
118.731
118.819
118.540
118.865
119.014
35
24
36
21
16
14
19
17
61
49
26
13
12
14
56
18
15
14
12
13
13
59
11
12
29
15
20
62
15
15
11
1,090
5
399
15
20
59
7
2
910
355
570
6
1
17
7
386
24
6
1
17
11
1,680
2
4
5,
2
60
121
6
3
1
.00
.75
.00
.80
.90
.40
.94
.28
.00
.00
.00
.46
.86
.40
.00
.00
.80
.54
.94
.50
.90
.00
.22
.63
200
.40
.70
.00
.93
.89
.90
Mean basin eleva
tion, in
feet
6,270
5,200
4,960
4,960
3,990
4,050
3,540
3,820
4,900
5,360
4,150
2,700
4,050
6,320
6,900
4,900
5,780
5,060
5,190
5,310
5,510
4,580
4,270
5,220
5,450
4,580
4,680
4,680
5,350
5,130
4,130
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
31.0
30.0
28.0
20.0
14.0
13.0
12.0
10.0
16.3
19.0
17.8
10.0
10.0
28.0
37.0
25.0
25.0
20.0
20.0
22.0
25.0
22.0
24.0
25.0
27.0
20.0
24.0
24.0
30.0
22.0
20.0
32.6
30.1
40.0
40.0
40.2
40.4
42.4
40.1
40.0
36.2
42.7
43.1
35.0
34.9
34.9
35.0
35.0
35.0
35.7
34.9
35.0
34.9
35.2
35.1
34.7
35.1
35.1
35.0
35.0
35.1
34.9
128 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
13191000
13196500
13200000
13200500
13207000
13207500
13210300
13213900
13214000
13216500
13227000
13228300
13229400
14036800
14037500
14038530
14038550
14038600
14038750
14038900
14039200
14040500
14040700
14040900
14041500
14041900
14042000
14042500
14043800
14043850
14043900
Relation characteristic L H D 0 U
0
0
1
0
0
0
1
-
1
1
0
0
-
0
1
1
-
0
-
-
1
0
0
1
0
-
0
0
0
0
-
1
0
0
0
0
0
0
-
0
0
0
0
-
0
1
0
-
0
-
-
1
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
0
-
0
0
0
0
-
1
0
0
-
0
-
-
0
1
1
0
0
-
0
0
0
0
-
0
1
0
0
0
0
0
-
0
0
0
0
-
0
0
0
-
0
-
-
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
1
0
1
1
0
0
0
0
0
1
0
0
0
0
1
Peak discharge (cubic indicated recurrence
2
4,9004,820
1314
1,8201,800
6162525594
1037473
242,0802,070
93993883584810197
2073749090
1,7301,690
1291820
21
1015657
2,8202,820
33333434
3,0803,020
24632614
1,0601,050
39404747
---_
5
7,5407,340
2428
2,9002,840
103108129136237259164158
413,8903,8701,4901,4902,3302,320
191178
35115122134133
2,8002,700
2282835
36
1777380
4,5804,590
75704447
4,5004,360
42993947
1,6001,580
59626867
10
9,5209,130
3442
3,7003,600
137150206223383433248236
635,4005,3601,9101,9303,8803,830
269247
53144160167164
3,6503,470
3103551
50
24884
1035,8805,950
1151035160
5,4105,170
621,2801,2002,0101,970
73828282
feet per interval
25
12,30011,600
4764
4,7704,620
186210335357636710381350
867,6807,5902,5002,5506,5406,290
388343
73181213216211
4,9004,590
4194575
67
33698
1387,6507,850
1791506079
6,5306,190
831,6901,5402,5602,490
91109100103
second) for (years)
50
14,60013,700
5982
5,6105,440
227261457478880960502452
1059,6409,5102,9803,0709,0508,560
494429
88208254258251
5,9605,570
5065394
80
407109165
9,0609,410
2391926794
7,3406,980
1002,0401,8403,0102,920
105131114120
100
17,00015,900
72100
6,4906,310
272315601614
1,1801,250
642568
12611,80011,6003,5003,62012,00011,200
615527
104235294304295
7,1406,640
59461
114
93
480120194
10,50011,000
30824073
1098,1207,770
1182,4302,1703,4803,370
121155128137
Maximum peak discharge
of record (cubic feet per second)
9,550
46
5,440
274
244
373
420
100
12,000
3,970
8,980
497
41
155
354
5,830
285
39
28
240
108
8,170
143
57
8,170
90
1,880
3,840
98
98
6621 36 54 73 88 105
Basin, Climatic, and Flood Characteriatics 129
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
14044000
14044100
14044500
14046250
14046300
14046400
14046900
14047350
14047450
14077500
14077800
14078000
14078200
14078400
14078500
14081800
14083000
13044500
13045500
13047500
13050800
13052200
13054400
13055000
13058000
13062700
13063000
13063500
13073700
13074000
13075000
Flood Station name region
Middle Fork John Day River at Ritter,Oreg.Paul Creek near Long Creek, Oreg.
Fox Creek at Gorge near Fox,Oreg.Ives Canyon near Spray, Oreg.
Big Service Creek near Service Creek,Oreg.Donnely Creek Tributary near ServiceCreek, Oreg.
John Day River Tributary near Clarno,Oreg.
Rock Creek Tributary near Hardman,Oreg.West Fork Dry Creek near Gooseberry,Oreg.North Fork Beaver Creek near Paulina,Oreg.
Wolf Creek Tributary near Paulina,Oreg.
Beaver Creek near Paulina,Oreg.Lizard Gulch Tributary near Hampton,Oreg.
Lookout Creek near Post, Oreg.
North Fork Crooked River above DeepCreek, Oreg.
Ahalt Creek near Mitchell, Oreg.
Ochoco Creek above Mill Creeknear Prineville, Oreg.Warm River at Warm River,Idaho
Robinson Creek at Warm River,Idaho
Falls River near Squirrel,Idaho
Moose Creek near Victor,Idaho
Teton River above South LeighCreek, near Driggs, Idaho
Milk Creek near Tetonia,Idaho
Teton River near St Anthony,Idaho
Willow Creek near Ririe,Idaho
Angus Creek near Henry,Idaho
Blackfoot River above reservoir,near Henry, Idaho
Little Blackfoot River at Henry,Idaho
Robbers Roost Creek near McCammon,Idaho
Birch Creek near Downey,Idaho
Marsh Creek near McCammon,Idaho
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Lati
tude , in decimal degrees
44.
44.
44.
44.
44.
44.
44.
45,
45.
44.
44.
44.
43.
44.
44.
44.
44.
44.
44.
44.
43.
43.
43.
43.
43.
42.
42.
42.
42.
42.
42.
.889
.724
.619
.860
.894
772
.906
,078
.286
.167
.277
.164
.589
.311
.333
,433
.308
.114
.116
069
,563
782
883
927
593
829
817
908
706
350
631
Longi
tude , in decimal degrees
119.
119.
119
119.
120.
120
120.
119.
119.
119
119
119
119
120.
120.
120.
120
111
111
111.
111.
111.
111.
111.
111.
111.
111.
111.
112.
112.
112.
.140
.132
,262
.714
.070
.003
.568
.569
.964
,733
,817
.922
,983
.240
.083
.351
.644
,324
.319
.240
.067
.208
.344
.615
769
338
.510
.529
203
250
225
System
atic Drainage years area, in of square
record miles
56
11
28
12
11
18
21
14
13
13
15
33
16
14
11
22
13
18
18
74
10
25
19
76
25
16
13
12
11
14
32
515.00
3.50
90.20
2.73
5.56
1.85
1.36
6.25
0.81
64.40
2.15
450.00
19.60
7.53
159.00
2.28
200.00
178.00
129.00
326.00
21.40
335.00
17.90
890.00
627.00
13.90
350.00
38.80
5.70
6.56
355.00
Mean basin eleva
tion, in
feet
4,800
4,490
4,830
3,460
3,880
2,880
3,730
4,100
2,540
4,670
5,150
4,600
5,000
5,670
5,130
5,130
4,654
6,830
6,450
7,520
8,300
7,350
6,540
6,900
6,390
7,000
6,940
6,600
6,910
7,240
5,630
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
23.0
18.0
21.0
18.0
18.0
16.0
15.0
20.0
15.0
20.0
18.0
20.0
15.0
25.0
21.0
25.0
21.0
27.0
27.0
46.0
24.0
36.0
20.0
26.0
16.0
18.0
25.0
18.0
20.0
24.0
19.0
33.7
34.7
35.4
34.7
34.7
34.8
35.1
34.9
34.7
35.1
35.1
35.1
37.7
34.0
35.2
34.5
34.7
37.7
37.6
37.6
38.2
37.9
38.5
40.0
40.0
35.4
35.8
36.3
40.0
40.0
40.0
130 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
14044000
14044100
14044500
14046250
14046300
14046400
14046900
14047350
14047450
14077500
14077800
14078000
14078200
14078400
14078500
14081800
14083000
13044500
13045500
13047500
13050800
13052200
13054400
13055000
13058000
13062700
13063000
13063500
13073700
13074000
13075000
Relation characteristic L H D 0 U
0
-
1
-
0
-
0
1
-
0
-
0
-
1
0
1
1
0
1
0
0
1
1
1
0
0
0
0
0
0
0
0
-
0
-
0
-
0
0
-
0
-
1
-
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
-
0
-
0
-
0
1
-
1
-
1
-
1
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
-
0
-
1
-
0
0
-
0
-
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
1
0
1
0
0
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
1,6501,640
32410407
____
2747
2030305756
11612587
231,3701,360
1094949
1,3901,320
3938
356371460462639636
3,5503,540
278274
1,5101,510
8282
3,3703,3601,7301,720274270
1,0401,040
14014014152425
322324
5
2,4302,420
55798785
467
17
3549478988
19781741
392,7502,700
1937174
1,7801,650
5756
540600628635805803
4,4504,440
338332
1,9101,910
244242
4,5404,5302,5502,520
511499
1,5201,51020921021233840
475482
10
2,9702,970
811,1501,120
759
33
606260
111114
34885844
544,0603,950
2758694
2,0401,870
7170
671834738753910910
5,0104,990
373365
2,1602,160
445435
5,3405,3203,1103,060
715689
1,8401,830
25725926314952
588603
feet per second) for interval (years)
25
3,6503,700
1101,7001,630
1031258
847976
139148
481,010
989
736,2705,980
375103121
2,3702,180
9289
8451,190
875910
1,0401,0505,7005,660
415407
2,4702,480
865828
6,3706,3303,8303,7501,030
9712,2502,230
32132733426573
743776
50
4,1704,280
1342,2102,090
1271477
1049288159175
601,1001,120
878,4007,910
457116142
2,6202,460
108105982
1,490976
1,0301,1301,1506,1906,140
445440
2,7002,7301,3501,2707,1707,1204,3804,2701,3201,2202,5502,540
37038237527890
869920
100
4,7004,870
1582,8102,620
1531797
127105101180203
731,1801,240
10111,00010,200
542129164
2,8702,770
127122
1,1201,7901,0801,1601,2201,2606,6806,620
473474
2,9202,9702,0201,8707,9807,9104,9304,7801,6401,5002,8502,840
420439426394
1101,0001,070
Maximum peak discharge
of record (cubic feet per second)
4,730
56
1,860
86
11
42
83
117
134
955
300
12,800
177
85
2,500
122
821
900
1,140
7,060
390
2,460
1,350
11,000
5,080
1,060
2,150
292
24
95
1,120
Basin, Climatic, and Flood Characteristics 131
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
13075600
13077700
13078000
13079000
13079200
13079800
13082500
13083000
13092000
13105000
13108500
13112000
13112900
13113000
13113500
13116000
13118700
13135500
13136500
13139500
13141400
13141500
13145700
13147900
13148000
13154000
09204500
09205000
09207650
09210500
09213500
Flood Station name region
North Fork Pocatello Creek nearPocatello, Idaho
George Creek near Yost, Utah
Raft River at Peterson Ranch,near Bridge, IdahoClear Creek near Naf, Idaho
Cassia Creek near Elba, Idaho
Heglar Canyon Tributary nearRock land, IdahoGoose Creek above Trapper Creek,near Oakley, IdahoTrapper Creek near Oekley, Idaho
Rock Creek near Rock Creek,Idaho
Salmon Falls Creek near SanJacinto, Nev.
Camas Creek at 18-MI SHRG CRL,near Kilgore, Idaho
Camas Creek at Camas, Idaho
Huntley Canyon at Spencer, Idaho
Beaver Creek at Spencer,Idaho
Beaver Creek at Dubois, Idaho
Medicine Lodge Creek at EllisRanch near Argora, IdahoLittle Lost River below Wet Creek,near Howe, IdahoBig Wood River near Ketchum,Idaho
Warm Springs Creek at Guyer Spring,near Ketchum, Idaho
Big Wood River at Hailey, Idaho
Deer Creek near Fair field,Idaho
Camas Creek near Blaine, Idaho
Schooler Creek near Gooding,Idaho
Little Wood River above High 5 Creek,near Carey, IdahoLittle Wood River at Campbell RH,near Carey, Idaho
Clover Creek near Bliss, Idaho
East Fork at Newfork, Wyo.
New Fork River near Big Piney, Wyo.
Dry Basin Creek near Big Piney,Wyo.Fontenelle Creek near HerschlerRanch, near Fontenelle, Wyo.
Big Sandy Creek near Farson, Wyo.
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
Lati
tude, in decimal degrees
42.886
41.919
42.068
41.967
42.276
42.474
42.125
42.169
42.356
41.944
44.297
44.003
44.364
44.356
44.186
44.292
44.139
43.786
43.683
43.518
43.370
43.333
43.192
43.492
43.461
43.025
42.700
42.567
42.424
42.096
42.317
Longi
tude, in decimal degrees
112.
113.
113.
113.
113.
113.
113.
113.
114.
114.
111.
112.
112.
112.
112.
112.
113.
114.
114.
114.
114.
114.
114.
114.
114.
115.
109.
109.
110.
110.
109.
396
481
449
286
514
146
939
972
303
687
906
220
183
178
236
501
244
424
415
319
719
541
657
058
047
006
717
929
110
416
485
System
atic Drainage years area, in of square
record miles
11
27
26
28
12
17
73
73
28
74
22
62
10
28
56
29
26
24
18
72
11
62
19
23
25
28
13
22
11
35
49
14.
7.
412.
19.
84.
7.
633.
53.
80.
1450.
210.
400.
4.
120.
220.
165.
440,
137.
96.
640.
13.
648.
2.
248.
267.
140.
348.
1,230.
47.
152.
322.
00
84
00
00
00
72
00
70
00
00
00
00
00
.00
00
00
,00
,00
00
00
,20
00
22
00
00
00
00
00
20
00
00
Mean basin eleva
tion, in
feet
5,800
8,570
6,150
7,870
6,560
5,300
6,030
6,360
6,330
6,020
6,970
6,800
7,110
7,260
7,520
8,120
7,560
7,670
6,440
5,600
5,640
7,220
7,160
4,700
8,380
8,370
7,280
8,160
7,820
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
10.0
25.0
24.0
28.0
35.0
15.0
22.0
18.0
15.0
15.0
25.0
--
17.0
25.0
22.0
25.0
41.0
37.0
35.0
20.0
18.0
12.0
28.0
27.0
10.0
18.0
17.0
12.0
18.0
14.0
40.0
40.1
40.0
40.0
39.9
40.0
40.0
40.0
41.3
40.0
37.3
40.1
36.8
37.0
39.7
36.6
35.0
30.1
30.1
32.9
37.4
40.4
40.5
38.2
39.6
44.4
37.6
40.1
40.0
39.3
40.2
132 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
13075600
13077700
13078000
13079000
13079200
13079800
13082500
13083000
13092000
13105000
13108500
13112000
13112900
13113000
13113500
13116000
13118700
13135500
13136500
13139500
13141400
13141500
13145700
13147900
13148000
13154000
09204500
09205000
09207650
09210500
09213500
Relation characteristicL
0
0
0
0
0
1
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
0
-
0
1
1
1
H
0
1
0
0
0
1
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
-
0
0
0
0
D
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
1
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1-
0
0
0
0
u
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
Peak discharge (cubic indicated recurrence
2
22237373
1491571171171921991541522552585354
187187734736791788441
910
340341267268105109345
914912488489
2,4102,410
5353
3,3003,290
2626
1,0701,070
861860
1,5801,570
1,1905,3105,270
136138492493843844
5
3839
1151153163351821834014133052985525598889
301301
1,2301,2301,3001,290
751
1719
547549454457154164405
1,2901,290
653657
3,4703,460
8788
5,2605,230
3838
1,5501,5401,4001,4003,1903,140
1,7406,9406,820
269274680687
1,1601,170
10
5053
148148483518231232592609453437856869116119379379
1,5901,6001,7101,690
959
2427711714601607192213441
1,5301,530
765775
4,2104,200
114117
6,6706,610
4646
1,8901,8801,8301,8204,7004,580
2,1307,9007,680
376385799816
1,3501,370
feet per interval
25
6874
196196782845299302903922713673
1,4001,420
157162478480
2,1002,1202,2902,2501,220
3541
950954813825245287483
1,8401,830
909932
5,1805,160
153159
8,5608,440
5756
2,3302,3002,4402,4107,2306,950
2,5908,9908,630
531540944983
1,6001,640
second) for (years)
50
8392
236235
1,0801,170
353357
1,1901,200
974904
1,9601,990
193201552557
2,5002,5302,7702,7001,400
4453
1,1501,160
9891,010289352513
2,0702,0701,0201,0605,9305,900
186195
10,0009,820
6565
2,6702,6402,9602,9109,6409,160
3,0009,7409,320
659667
1,0501,1101,7701,840
100
99112281280
1,4701,580
412418
1,5301,5201,3101,2002,6702,700
233244625634
2,9202,9603,3003,2001,570
5567
1,3701,3701,1801,200
337425542
2,3002,3001,1301,1806,6906,650
223236
11,60011,300
7474
3,0102,9703,5303,46012,50011,700
3,35010,4009,930
797796
1,1501,2401,9402,030
Maximum peak discharge
of record (cubic feet per second)
57
295
2,060
386
982
1,930
3,240
270
461
3,860
2,590
1,320
36
1,190
858
361
509
1,690
961
6,150
150
9,780
68
2,480
3,110
4,500
2,940
9,190
450
907
1,890
Basin, Climatic, and Flood Characteristics 133
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09215000
09216290
09216350
09216537
09216550
09216560
09216600
09216700
09221680
09221700
09223500
09224000
09224800
09224810
09224820
09224840
09224980
09225200
09225300
09229450
09266500
09270000
09270500
09271000
09273500
09275500
09277500
09279000
09279500
09287500
09288000
Station name
Pacific Creek near Parson, Wyo.
East Otterson Wash near GreenRiver, Wyo.Skunk Canyon Creek near GreenRiver, Wyo.Delaney Draw near Red Desert,Wyo.Deadman Wash near Point Of Rocks,Wyo.
Bitter Creek near Point Of Rocks,Wyo.Cutthroat Draw near Rock Springs,Wyo.Salt Wells Creek near Rock Springs,Wyo.Mud Spring Hollow near ChurchButte near Lyman, Wyo.
Mud Spring Hollow near Lyman, Wyo.
Hams Fork near Frontier, Wyo.
Hams Fork at Diamondville, Wyo.
Meadow Springs Wash Tributarynear Green River, Wyo.Blacks Fork Tributary No 2near Green River, Wyo.
Blacks Fork Tributary No 3near Green River, Wyo.Blacks Fork Tributary No 4near Green River, Wyo.Summers Dry Creek near Green River,Wyo.Squaw Hollow near Burntfork, Wyo.
Green River Tributary No 2 nearBurntfork , Wyo .
Henrys Fork Tributary near Manila,Utah
Ashely Creek near Vernal, Utah
Dry Fork below Springs nearDry Fork, Utah
Dry Fork at Mouth near Dry Fork,Utah
Ashley Creek, Sign of the Mainenear Vernal, UtahHades Creek near Hanna, Utah
West Fork Duchesne River nearHanna , Utah
Duchesne River near Tabiona, Utah
Rock Creek near Mountain Home,Utah
Duohesne River at Duchesne, Utah
Water Hollow near Fruitland, Utah
Currant Creek near Fruitland, Utah
Flood region
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Lati
tude , in decimal degrees
42
41
41
41
41
41
41
41
41
41
41
41
41
41
41
41
41
41
41
41
40
40,
40
40,
40,
40.
40.
40,
40.
40.
40.
.130
.784
.732
.639
.675
.678
.457
.483
.385
.383
.857
.783
.544
.460
.425
.411
.374
.171
.061
.021
.577
.569
.526
.517
.536
,450
.134
.493
,164
.242
.200
Longi
tude, in decimal degrees
109.323
109.734
109.511
108.129
108.736
108.786
108.942
108.967
110.187
110.183
110.562
110.533
109.760
109.622
109.615
109.601
109.644
109.609
109.618
109.679
109.621
109.697
109.605
109.596
110.867
110.884
110.602
110.577
110.393
110.980
110.907
System
atic Drainage years area, in of square
record miles
19
16
11
24
21
15
22
18
20
13
27
18
18
18
20
18
16
20
22
10
74
22
32
31
19
42
35
49
36
26
40
500.00
16.60
15.70
32.80
152.00
758.00
7.88
515.00
8.83
10.20
298.00
86.00
5.22
12.00
3.59
1.26
423.00
6.57
13.00
3.15
101.00
97.40
115.00
241.00
7.50
61.60
356.00
147.00
660.00
13.80
140.00
Mean basin eleva
tion, in
feet
7,270
6,410
6,940
7,040
7,000
7,010
6,920
7,340
6,800
6,770
8,130
7,910
6,370
6,650
6,570
6,570
6,880
6,610
6,540
6,600
9,440
9,360
9,190
9,100
9,730
8,840
8,770
10,000
8,770
8,380
8,360
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
10,
7
8
7
8
7,
8
9
9
9
9
18
8
8
9
9
12,
15
16
17,
23,
27.
23,
23.
30.
26.
25.
31.
24.
22.
24.
.0
.0
.0
.0
.0
.5
.0
.5
.0
.0
.2
.0
.0
.5
.0
.0
.0
.0
.0
.0
.0
.5
.0
o
.3
,6
.6
,6
.1
.1
,6
41.0
45.3
48.5
45.6
44.7
44.6
44.5
44.6
41.7
41.7
39.3
39.5
46.7
49.0
48.5
48.4
47.2
43.5
41.3
39.1
35.6
35.3
36.6
36.7
35.0
35.0
36.9
35.0
38.8
35.0
35.0
134 Methods for Estimating Magnituda and Frequency of Flooda in tha Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09215000
09216290
09216350
09216537
09216550
09216560
09216600
09216700
09221680
09221700
09223500
09224000
09224800
09224810
09224820
09224840
09224980
09225200
09225300
09229450
09266500
09270000
09270500
09271000
09273500
09275500
09277500
09279000
09279500
09287500
09288000
Relation characteristic L H D 0 U
0
1
0
1
0
1
-
1
1
1
0
1
-
-
1
-
0
-
-
-
1
1
1
1
1
1
1
1
1
0
1
0
1
1
1
0
0
-
0
0
0
0
0
-
-
0
-
1
-
-
-
0
0
0
1
0
0
0
0
0
0
1
1
0
0
0
0
1
-
0
0
0
0
0
-
-
0
-
0
-
-
-
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
-
0
0
0
0
0
-
-
0
-
0
-
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
1
0
1
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
25927416115915179191
397397466485
481,1201,120
63639493
1,1501,1501,5501,540____
28 -
572323
11624627
37
58
221,0701,070
521524547549
1,4001,400
8182
486485
1,4001,4001,6401,6402,7802,770
2830
323326
5
5566093503374351
267266728726956
1,020
882,1802,160
194189178173
1,6201,6202,1402,120
56
1087372
231,6401,620
71
Ill
431,5601,550
761767900902
2,0001,990
105108607607
1,8001,8002,0502,0403,4103,400
6065
496506
10
8059195354998197
482471996989
1,3801,520
1213,0202,950
342325251238
1,9101,9102,5502,510
80
150138132
322,6502,560
99
154
601,9101,890
922934
1,1701,1702,4302,400
121128677679
2,0502,0602,3102,2903,8003,790
90100634656
feet per second) for interval (years)
25
1,1701,390
852755174192923868
1,3901,3702,0402,280
1634,1904,000
619560366333
2,2502,2503,0803,010
112
206278253
454,3704,040
137
212
832,3802,3401,1301,1501,5401,5303,0102,940
142156756764
2,3402,3802,6302,5804,2504,250
141158838878
50
1,4701,7801,160
992295301
1,4201,3001,7101,6702,6202,940
1995,1404,830
903790469414
2,5002,5203,4903,410
139
253445391
565,9805,360
169
262
1032,7502,6901,2801,3001,8501,8203,4603,360
157177809825
2,5502,6102,8702,8104,5704,590
188209
1,0101,070
100
1,8002,1901,5401,270
487452
2,1001,8602,0702,0003,2703,640
2336,1405,6801,2601,070
589505
2,7302,7603,9103,810
165
297687582
667,8806,830
199
309
1223,1403,0501,4301,4602,1802,1203,9303,790
173198858884
2,7502,8403,1103,0304,8804,930
245268
1,1001,280
Maximum peak discharge
of record (cubic feet per second)
972
791
600
1,260
1,320
1,650
700
3,750
557
406
2,450
3,250
170
180
245
47
13,900
620
3,360
588
3,500
974
1,920
4,110
156
758
5,260
2,920
4,420
133
1,260
Basin, Climatic, and Flood Characteristics 135
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09288150
09288500
09288900
09292500
09297000
09298000
09299500
09312500
09312600
09312700
09312800
10014000
10015700
10016000
10019000
10019700
10021000
10023000
10027000
10032000
10040000
10040500
10041000
10047500
10058600
10069000
10072800
10084500
10090800
10093000
10099000
Flood Station name region
West Fork Avintaquin nearFruitland, UtahStrawberry River at Duchesne,Utah
Sowers Creek near Duchesne, Utah
Yellowstone River near Altonah,Utah
Uinta River near Neola, Utah
Farm Creek near Whiterocks, Utah
Whiterocks River near Whiterocks,Utah
White River near Soldier Summit, Utah
White River below Tabbyune Creeknear Soldier Summit, UtahBeaver Creek near Soldier Summit,Utah
Willow Creek near Castle Gate, Utah
Bear River above Sulphur Creeknear Evanston, Wyo.Sulphur Creek above Reservoirnear Evanston, Wyo.Sulphur Creek near Evanston,Wyo.Bear River near Evanston, Wyo.
Whitney Canyon Creek nearEvanston, Wyo.
Woodruff Creek near Woodruff,Utah
Big Creek near Randolph, Utah
Twin Creek at Sage, Wyo.
Smiths Fork near Border, Wyo.
Thomas Fork near Geneva, Idaho
Salt Creek near Geneva, Idaho
Thomas Fork near Wyoming-IdahoState line
Montpelier Creek at Weir,Montpelier, IdahoBloomington Creek at Bloomington,Idaho
Georgetown Creek near Georgetown,Idaho
Eightmile Creek near Soda Springs,Idaho
Cottonwood Creek near Cleveland,Idaho
Battle Creek Tributary nearTreasurton, Idaho
Cub River near Preston, Idaho
High Creek near Richmond, Utah
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Lati
tude, in decimal degrees
39
40
39
40
40
40
40
39
39
39
39
41
41
41
41
41.
41.
41.
41.
42.
42.
42.
42.
42.
42.
42.
42.
42.
42.
42.
41.
.993
.161
.989
.512
.536
.567
.565
.922
.876
.831
.777
.167
.144
.158
.314
.428
.482
.610
.810
,281
.392
400
,403
.330
185
496
537
332
278
141
978
Longi
tude , in decimal degrees
110
110
110
110
110
109
.814
.411
.459
.341
.063
.961
109.927
111
111
110
110
110
110
110
111
110
111
111
110
110
110
110
111
111
111
111
111
111.
111.
111.
111.
.057
.037
.969
.792
.880
.805
.858
.012
.972
.266
.253
.970
.868
.983
.992
.025
.237
.425
.314
.572
,774
,814
,689
744
System
atic Drainage years area, in of square
record miles
22
57
22
42
57
31
67
28
19
26
24
10
28
17
43
17
27
26
24
45
12
12
37
30
26
19
26
48
19
44
19
56.10
950.00
40.60
132.00
163.00
14.90
113.00
53.00
75.60
26.10
62.80
282.00
64.20
80.50
715.00
8.93
56.80
52.20
246.00
165.00
45.30
37.60
113.00
49.50
24.00
22.20
22.60
61.70
4.50
31.60
16.20
Mean basin eleva
tion, in
feet
8,313
7,660
8,118
10,440
10,710
9,181
10,370
8,360
8,150
8,750
8,120
9,370
8,050
7,930
8,130
7,300
7,900
7,370
7,270
8,270
7,170
7,390
7,290
7,370
7,860
7,830
7,710
6,650
5,810
6,890
7,700
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
22.1
23.7
17.4
32.6
32.7
23.1
32.1
26.3
25.4
21.0
14.0
23.8
14.0
16.0
19.8
12.0
25.8
19.9
14.0
32.1
19.0
23.0
29.0
26.7
31.0
30.3
24.0
22.8
19.0
24.1
40.4
35.0
38.6
37.9
34.4
35.0
35.1
35.0
35.1
35.3
35.5
36.2
35.1
35.1
35.2
35.7
36.7
35.3
35.4
37.1
37.4
36.9
36.9
36.8
35.9
35.1
35.6
34.9
36.4
36.5
35.4
35.7
136 Methods for Estimsting Msgnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09288150
09288500
09288900
09292500
09297000
09298000
09299500
09312500
09312600
09312700
09312800
10014000
10015700
10016000
10019000
10019700
10021000
10023000
10027000
10032000
10040000
10040500
10041000
10047500
10058600
10069000
10072800
10084500
10090800
10093000
10099000
Relation characteristic L H D 0 U
1
1
1
0
1
1
1
1
1
1
1
0
1
0
1
0
1
1
0
1
1
0
0
1
1
1
1
1
1
1
0
0
0
0
0
1
0
1
1
1
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
1
0
0
1
0
1
1
0
1
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
291292
1,0901,100
5559
1,0301,0301,3901,390
8889
1,1401,140
1741763143154851
225227
1,9001,880
406405512509
1,9401,940
4344
2612617577
2192259789751441451621624774769798
1521525153
1221223743725150
592588234231
5
670663
1,6401,660
158167
1,3801,3802,0802,070
167169
1,7401,730
2943004864908796
407411
2,3402,300
815805782771
2,5602,560
8385
342346123132502522
1,3101,300
2492542932939169081411471951978188
1711735625588785
713703338330
10
1,0401,0102,0602,110
276291
1,6201,6202,5902,570
231234
2,1602,140
398410622631121139565570
2,6202,5601,2301,200
966943
2,9502,960
118120395406162182748788
1,5301,520
331342393392
1,2401,220
172188222228104120205211690682113109789770417401
feet per second) for interval (years)
25
1,6801,5702,6602,750
508518
1,9201,9103,2903,230
325328
2,7302,680
559576819831173205812810
2,9402,8601,9801,8701,2001,1603,4303,470
172175460486219261
1,1201,1901,8001,780
445466531525
1,6601,610211247253268137170249262854840147139882852529498
50
2,3002,0903,1503,290
757748
2,1502,1403,8503,750
403403
3,1603,080
704723986998219264
1,0301,0203,1603,0902,7602,5401,3801,3203,7603,840
219221509552268330
1,4201,5102,0001,980
539569640631
1,9801,910
241296274300164213283305976959173163950913622577
100
3,0502,6903,6903,8701,0901,0402,3902,3604,4404,290
487482
3,6203,510
873886
1,1701,170
271325
1,2901,2503,3803,3203,7603,3801,5601,4904,0904,210
274272558617323404
1,7601,8602,2102,190
638673753736
2,3002,200
271346295332193256318347
1,1001,080
199187
1,020978724662
Maximum peak discharge
of record (cubic feet per second)
1,830
3,490
451
2,240
5,000
350
4,640
1,120
962
204
836
2,970
8,400
1,220
2,690
160
528
337
853
2,100
418
382
1,860
224
249
162
310
1,090
152
1,070
702
Basin, Climatic, and Flood Characteriatics 137
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10102300
10104700
10104900
10105000
10107800
10109001
10113500
10119000
10128200
10128500
10129350
10131000
10132500
10133700
10135000
10137500
10137680
10137780
10139300
10141500
10142000
10142500
10143000
10143500
10144000
10145000
10146000
10146900
10147000
10147500
10148200
Flood Station name region
Summit Creek above diversions.near Smithfield, Utah
Little Bear River below DavenportCreek, near Avon, Utah
East Fork Little Bear River aboveReservoir, near Avon, UtahEast Fork Little Bear River nearAvon , UtahTemple Fork near Logan, Utah
Logan River above State Damnear Logan, UtahBlacksmith Fork above U P & L,Colorado Dam near Hyrum, Utah
Little Malad River above ELkhornReservoir, near Malad, IdahoSouth Fork Weber River nearOakley, Utah
Weber River near Oakley, Utah
Crandall Creek near Peoa, Utah
Chalk Creek at Coalville, Utah
Lost Creek near Croydon, Utah
Threemile Creek near Park City,Utah
Hardscrabble Creek near Porterville,Utah
South Fork Ogden River nearHuntsville, Utah
North Fork Ogden River near Eden,Utah
Middle Fork Ogden River abovediversion, near Huntsville, Utah
Wheeler Creek near Huntsville,Utah
Holmes Creek near Kaysville, Utah
Farmington Creek above Diversions nearFarmington, Utah
Ricks Creek above Diversions,near Cent ervi lie, UtahParrish Creek above Diversions,near Centerville, UtahCenterville Creek above Diversions,near Centerville, UtahStone Creek above Diversionsnear Bountiful, UtahMill Creek at Mueller Park,near Bountiful, UtahSalt Creek at Nephi, Utah
Utah Lake Tributary nearElberta, Utah
Summit Creek near Santaquin, Utah
Payson Creek above Diversions,near Payson, Utah
Tie Fork near Soldiers Summit,
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Lati
tude, in decimal degrees
41
41
41
41
41
41
41
42
40
40
40
40
41
40
40
41
41
41
41
41
41
40.
40.
40.
40.
40.
39.
40.
39.
39.
39.
.869
.512
.518
.517
.833
.744
.622
.333
.749
.736
.775
.921
.176
.726
.954
.269
.390
.333
.254
.055
.001
.940
.924
.916
.894
.864
.713
017
922
969
950
Longi
tude , in decimal degrees
111
111
111
111
111
111
111
112
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
111
.758
.811
.714
.750
.583
.784
.739
.433
.219
.246
.364
.401
.406
.562
.716
.673
.914
.734
.842
.894
.872
.867
.864
.862
.844
.836
.804
.983
.753
.693
.216
System
atic Drainage years area, in of square
record miles
18
26
23
13
12
83
72
32
10
82
10
61
28
13
29
45
11
11
27
17
33
17
19
30
16
19
42
12
19
15
22
11.60
61.60
56.70
49.70
15.40
214.00
268.00
120.00
16.00
163.00
12.00
253.00
123.00
2.68
28.10
137.00
6.03
31.30
11.10
2.49
10.00
2.35
2.08
3.15
4.48
8.79
95.60
4.71
14.60
18.80
19.40
Mean basin eleva
tion, in
feet
7,590
6,730
7,350
7,370
7,290
7,460
7,150
6,080
8,780
9,090
7,700
7,540
7,320
7,340
7,220
7,960
7,170
7,250
6,620
7,560
7,470
7,360
7,090
6,940
7,050
7,370
7,490
5,530
8,400
7,610
7,500
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
34.1
28.6
26.9
27.4
--
33.8
25.1
23.9
30.5
32.1
24.0
22.0
19.2
32.0
33.0
27.0
32.0
27.4
27. 2
33.8
37.6
31.2
31.0
30.1
31.0
32.7
19.2
__
26.4
26.3
26.0
35.6
35.6
34.8
35.0
35.0
35.8
35.4
39.9
35.0
35.0
35.0
36.2
35.6
34.9
39.3
36.0
38.6
34.9
38.7
39.8
39.5
40.1
40.0
39.9
39.5
39.8
44.5
45.0
43.5
42.4
35.6Utah
138 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10102300
10104700
10104900
10105000
10107800
10109001
10113500
10119000
10128200
10128500
10129350
10131000
10132500
10133700
10135000
10137500
10137680
10137780
10139300
10141500
10142000
10142500
10143000
10143500
10144000
10145000
10146000
10146900
10147000
10147500
10148200
Relation characteristic L H D 0 U
1
0
1
0
0
1
1
0
0
1
1
1
0
0
1
1
0
1
1
0
0
1
1
1
0
0
1
-
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
0
0
0
0
0
-
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
1
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
Peak discharge (cubic indicated recurrence
2
1481474994944964923153126061
1,1001,100
529530107108197196
1,8501,850
9090
5535542272291011
2542528048029089
4534421301291718
14814722221415151524244041
213214
177778
1371363335
5
21020679878268166952351196
1001,4501,450
848851241247226227
2,4002,390
1231258218263994071517
349345
1,2201,210
1191165605352542492829
23523231322122222349507274
365370
391201242572539296
10
251245
1,020985810788681655121132
1,6801,6701,0801,090
388400242249
2,7602,730
144151
1,0101,020
5375551824409403
1,4901,470
1381346285873643503639
297290373925272729727396
100491501
59150159355344164171
feet per second) for interval (years)
25
301292
1,3301,260
978941904847155179
1,9601,9501,4001,420
668684261282
3,2303,180
170188
1,2701,300
7347692335
482474
1,8201,790
1621587126525425074651
380366455030363439
107108128136682700
88191208498469316318
50
337327
1,5801,4701,1101,0601,0901,010
182218
2,1802,1701,6401,670
971981273310
3,5903,520
188218
1,4701,510
8999492745
533527
2,0602,020
1791777747087046455362
444424515934433947
138138155168849873
113224248619572492477
100
374364
1,8501,7001,2401,1801,2801,160
210257
2,3902,3801,9001,9401,3801,370
284338
3,9503,860
205247
1,6801,7401,0801,140
3155
584581
2,3002,250
1961978347658958056072
510483576838504455
173171182198
1,0401,070
137257287750679742691
Maximum peak discharge
of record (cubic feet per second)
302
1,540
1,110
960
124
2,480
1,650
1,450
259
4,170
134
1,570
770
24
464
1,890
156
744
600
36
366
51
30
35
82
140
832
2,210
215
465
1,200
Basin, Climatic, and Flood Characteristics 139
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10148300
10148400
10148500
10152500
10153200
10153800
10158500
10160000
10160800
10164500
10165500
10166400
10166430
10167500
10172200
13018300
13019500
13020000
13025000
13027000
13027200
13029500
13030000
13030500
13032000
10265200
10265700
10266200
10267000
10268700
10276000
Station name
Dairy Fork near Thistle, Utah
Nebo Creek near Thistle, Utah
Spanish Fork at Thistle, Utah
Hobble Creek near Springeville,Utah
Big Cove Wash near Lehi, Utah
North Fork Provo River near Kamas,Utah
Round Valley Creek near Wallsburg,UtahDeer Creek near Wildwood, Utah
North Fork Provo River atWildwood, UtahAmerican Fork above Powerplant,near American Fork, UtahDry Creek near Alpine, Utah
Tickville Gulch near Cedar Valley,Utah
West Canyon Creek near Cedar Fort,Utah
Little Cottonwood Creek near SaltLake City, Utah
Red Butte Creek at Fort Douglas,near Salt Lake City, UtahCache Creek near Jackson, Wyo.
Hoback River near Jackson, Wyo.
Fall Creek near Jackson, Wyo.
Swift Creek near Afton, Wyo.
Strawberry Creek near Bedford,Wyo.
Bear Canyon near Freedom, Wyo.
McCoy Creek above Reservoir,near Alpine, IdahoIndian Creek above Reservoir,near Alpine, Idaho
Elk Creek above Reservior,near Irwin, IdahoBear Creek above Reservoir,near Irwin, Idaho
Convict Creek near Mammoth Lakes,Calif.
Rock Creek at Little RoundValley near Bishop, Calif.Paradise Creek near Paradise,Calif.Pine Creek at Division Boxnear Bishop, Calif.Silver Canyon Creek near Laws,Calif.Big Pine Creek near Big Pine,Calif.
Flood region
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
Lati
tude, in decimal degrees
39
39
39
40
40
40
40,
40
40
40
40.
40
40.
40
40,
43,
43
43.
42.
42,
42,
43.
43.
43.
43.
37.
37.
37.
37.
37.
37.
.967
.872
.999
.158
.233
.597
.408
.404
.371
.448
.476
.383
.407
.578
.780
.452
.299
.316
.725
.903
.977
.181
.260
.324
.283
607
554
462
416
408
145
Long i - tude, in decimal degrees
111.
111.
111.
111.
111.
111.
111.
111.
111.
111.
111.
112.
112.
111.
111.
110.
110.
110.
110.
110.
111.
111.
111.
111.
111.
118.
118.
118.
118.
118.
118.
350
569
499
527
883
097
475
532
566
681
757
000
101
797
805
703
669
738
900
900
196
115
067
111
221
348
684
576
621
279
314
System
atic Drainage years area, in of square
record miles
14
10
60
43
13
23
12
11
10
59
23
14
11
51
23
42
14
12
38
12
11
21
18
18
22
38
52
11
58
49
62
11.00
36.70
490.00
105.00
0.44
25.00
71.90
26.00
12.30
51.10
9.82
15.60
26.80
27.40
7.25
10.60
564.00
46.80
27.40
21.30
3.30
108.00
36.80
59.20
77.10
18.20
35.80
4.75
36.40
19.70
39.00
Mean basin eleva
tion, in
feet
6,950
7,540
7,130
7,110
5,190
9,550
6,960
7,450
8,100
8,460
8,770
5,740
7,630
8,680
6,800
8,430
8,000
7,500
8,550
8,470
7,200
6,960
7,790
7,670
7,130
10,000
10,500
--
10,000
--
7,200
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
20.5
21.4
21.4
26.9
--
33.0
--
31.7
36.6
43.0
--
--
--
--
29.2
24.0
24.0
25.0
17.9
25.0
27.0
24.0
25.0
32.0
25.0
27.0
27.0
11.0
31.0
7.0
22.0
37.2
41.1
39.2
38.5
43.3
35.0
35.0
35.0
34.9
36.2
37.4
43.5
42.8
39.7
40.2
35.0
34.9
35.1
36.7
35.7
35.5
36.6
36.8
37.7
38.3
40.0
40.0
40.0
40.0
40.0
48.8
140 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10148300
10148400
10148500
10152500
10153200
10153800
10158500
10160000
10160800
10164500
10165500
10166400
10166430
10167500
10172200
13018300
13019500
13020000
13025000
13027000
13027200
13029500
13030000
13030500
13032000
10265200
10265700
10266200
10267000
10268700
10276000
Relation characteristic L H D 0 U
1
0
1
1
-
1
1
1
0
1
0
0
-
0
0
0
0
1
1
1
1
1
0
0
1
1
0
-
1
1
0
0
1
1
0
-
0
0
0
0
1
1
0
-
0
0
0
0
1
0
0
1
0
0
0
0
0
0
-
0
0
0
1
0
0
0
-
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
1
0
0
0
0
0
-
0
0
0
1
0
0
0
-
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
Peak discharge (cubic indicated recurrence
2
152150109112518521258259
34074051161206466
1041043503501981972828
15038538419208080
3,8103,750
3803755024992602574545
842832200200463459514510105105114115
239239
2 -
184184
5
405386208216763776464466
75245181551738698
1471494814812782747879
2485125093840
119120
4,8504,680
5084966226153203167876
1,1901,160258261592584672663155152172170
7313310
44
256253
10
691631294309948980624628
11599588181227100128178183571572335326132133
3245965905559
145147
5,4905,180
598580697684356353106101
1,4101,360
294305670660768755189192212219
80358360
513
304306
feet per second) for interval (years)
25
1,2401,060
429447
1,2101,280
852858
17690671214315116176220231687689411393231226
4177046928492
179184
6,2705,760
716691788766399401148137
1,6601,570
337364762755878866234238263273
412415
6
365376
50
1,8301,490
549565
1,4301,5401,0401,050
22756733238393127218253270776780472446331315
497785770111122203211
6,8306,200
809784854827429440186168
1,8401,730
368414826829955952269274301314
450455
7
409432
100
2,6102,030
689690
1,6601,8101,2401,250
27822794263472138259288310866872536501455420
568868849144156228239
7,3806,650
905878919888458479228200
2,0001,880
398463886902
1,0301,040
304310339354
486492
9
454491
Maximum peak discharge
of record (cubic feet per second)
980
478
1,800
1,250
8
728
201
99
225
1,000
597
236
1,660
762
105
225
6,160
780
793
396
180
1,670
350
870
784
290
312
238
509
10
458
Basin, Climatic, and Flood Characteristics 141
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10276200
10281800
10282480
10286000
10287210
10289000
10291500
10292000
10292300
10295200
10295500
10296000
10296500
10296800
10299100
10299120
10302010
10304500
10306000
10308100
10308200
10308800
10309000
10309005
10310000
10310400
10310500
10311000
10311100
10311200
10311450
Flood Station name region
Deadman Creek near Big Fine,Calif.Independence Creek below FinyonCreek near Independence, Calif.
Mazourka Creek near Independence,Calif.
Cottonwood Creek near Olancha,Calif.
Bridgeport Creek near Bodie, Calif.
Virginia Creek near Bridgeport,Calif.Buckeye Creek near Bridgeport,Calif.Swager Creek near Bridgeport,Calif.
Bridgeport Reservoir Tributary nearBridgeport, Calif.
West Walker River at Leavitt Meadowsnear Coleville, Calif.Little Walker River near Bridgeport,Calif.
West Walker below Lake Walkernear Coleville, Calif.
West Walker River near Coleville,Calif.Slinkard Creek Tributary nearTopaz, Calif.
Desert Creek near Wellington,Nev.O'Banion Canyon near Wellington,Nev.
Reese River Canyon near Schurz,Nev.Silver Creek below Pen Creek nearMarkleeville, Calif.Hot Springs Creek near Markleeville,Calif.Milberry Creek at Markleeville,Calif.
East Fork Carson River below M'vlleCreek near Markleeville, Calif.Bryant Creek near Gardenerville,Nev.
East Fork Carson River nearGardenerville, Nev.Bodie Flat Tributary nearGardenerville, Nev.
West Fork Carson River at Woodfords,Calif.
Daggett Creek near Genoa, Nev.
Clear Creek near Carson Ctiy, Nev.
Carson River near Carson City, Nev.
Kings Can Creek near Carson City,Nev.
Ash Can Creek near Carson City,Nev.
Brunswick Canyon near New Empire,Nev.
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
Lati
tude, in decimal degrees
37.
36.
36.
36.
38.
38.
38.
38.
38.
38.
38
38.
38
38.
38.
38.
38,
38.
38
38.
38
38.
38.
38.
38.
38.
39,
39.
39.
39.
39.
144
779
,847
,439
,079
,192
.239
,283
.287
.331
.361
,380
.515
,647
.649
,635
.850
.600
.700
.700
.714
.794
.847
.835
.769
.965
,113
108
,154
176
.172
Longi
tude, in decimal degrees
118.121
118.264
118.085
118.080
119.044
119.208
119.325
119.299
119.214
119.551
119.444
119.449
119.454
119.561
119.325
119.264
118.782
119.775
119.850
119.783
119.764
119.672
119.703
119.631
119.832
119.849
119.797
119.711
119.807
119.804
119.686
System
atic Drainage years area, in of square
record miles
10
56
12
68
11
22
26
22
11
23
42
49
61
11
15
17
20
27
11
11
26
16
67
14
71
18
31
48
10
10
20
2.
18.
15,
40.
13,
63.
44
52,
0
73,
63
181
250
0,
50
5
14
19
14
5
276
31
356
0,
65
3,
15
886
4
5,
12
,48
.10
.60
.10
.10
.60
.10
.80
.79
.40
.10
.00
.00
.14
.40
.05
.00
.60
.40
.10
.00
.50
.00
.46
.40
.82
.50
.00
.06
.20
.70
Mean basin eleva
tion, in
feet
9,000
10,000
--
8,330
8,960
8,160
8,870
8,870
8,510
8,720
8,240
6,000
8,320
7,140
6,240
8,470
7,990
7,010
7,990
7,320
7,410
6,490
8,050
7,180
6,900
7,100
7,000
7,500
5,770
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
10.0
23.0
6.0
19.0
19.0
20.0
35.0
25.0
12.0
50.0
35.0
35.0
25.0
18.0
14.0
12.0
10.0
40.0
40.0
25.0
35.0
9.0
17.6
10.0
16.0
20.0
17.0
12.0
12.0
12.0
10.0
39.5
79.4
49.2
75.3
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
44.4
40.4
50.5
48.5
50.0
39.9
40.0
40.0
40.0
40.0
40.1
40.0
40.0
41.2
48.0
51.1
46.1
45.3
50.2
142 Methods for Estimeting Magnitude and Frequency of Floods in the Southwestarn United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10276200
10281800
10282480
10286000
10287210
10289000
10291500
10292000
10292300
10295200
10295500
10296000
10296500
10296800
10299100
10299120
10302010
10304500
10306000
10308100
10308200
10308800
10309000
10309005
10310000
10310400
10310500
10311000
10311100
10311200
10311450
Relation characteristic L H D 0 U
_
0
-
1
0
0
0
0
0
0
0
0
0
-
0
-
1
0
0
0
0
0
0
-
1
1
0
0
0
-
0
_
0
-
0
0
0
0
0
0
0
0
0
0
-
0
-
1
0
1
0
0
0
0
-
0
1
0
0
0
-
0
_
0
-
0
0
0
0
0
0
0
0
0
0
-
0
-
0
1
0
0
0
0
0
-
0
0
0
0
0
-
1
_
0
-
0
0
0
0
0
1
0
0
0
0
-
0
-
0
0
0
0
0
0
0
-
0
1
0
0
0
-
0
1
0
1
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
Peak discharge (cubic indicated recurrence
2
____
5353
120120
8
101103390390868844
1,1801,170
336336
1,8501,8501,8001,800
16670
333434
4254234094032525
2,8902,880
7678
2,6102,610
485885717172930
2,6302,630
2021
4766
5
____
48685
142082063332
2612555775632072032826
1,5801,530
568560
2,8302,7902,6202,590
1130128
12145141749730684643159150
5,8005,650219212
4,7304,680
21,4401,430
27266766
5,7805,710
5249
154746
10
____
40108110
1602752756891
4494847077073323687568
1,8501,800
756765
3,5603,5203,1803,180
7186262
139320322
1,0401,000
917840393360
8,4008,130
385412
6,6306,590
211,9601,940
3543
103120
9,0509,150
8694
176128147
feet per interval
25
.___
137141
368366147
827878877880558626208177
2,2102,1301,0301,0504,5504,4803,9003,930
16272426
238768759
1,5201,4401,2801,130
993850
12,50011,900
709763
9,7109,640
412,8302,790
4769
162207
15,00015,200
147168
286350400
second) for (years)
50
____
157163
444440238
1,2501,3001,0101,020
785877396322
2,4902,4001,2701,3005,3405,2404,4504,510
26350579
3361,3701,3201,9601,8301,6001,3901,7701,45016,20015,2001,0601,130
12,60012,500
633,6503,590
5896
217297
21,20021,500
208245
394649734
100
____
177185
525517367
1,8401,8501,1401,1601,0701,180
702547
2,7802,6701,5401,5806,1806,0505,0005,100
40438749
4542,3302,2002,5002,3001,9701,6802,9302,300
20,50019,0001,5201,600
16,00015,800
944,6404,540
70130282408
29,10029,300
285344
5241,1001,220
Maximum peak discharge
of record (cubic feet per second)
4
169
1,300
520
115
1,300
947
585
98
2,810
1,510
6,220
6,500
640
262
336
1,870
2,220
1,740
291
15,100
975
17,600
3
4,890
63
170
30,000
48
584
90
Basin, Climatic, and Flood Characteristics 143
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10312012
10312015
10312050
10336600
10336635
10336660
10336693
10336780
10339400
10339900
10340500
10342000
10343500
10348900
10350100
09415480
09415560
09415600
09415800
09418100
09418150
09418450
09418500
10172700
10172720
10172740
10172760
10172790
10172800
10172810
10172830
Flood Station name region
Adrian Valley Tributary nearWabuska, Nev.Adrian Valley Tributary nearWeeks, Nev.Lahontan Reservoir Tributary nearSilver Spur, Nev.
Upper Truckee River nearMyers, Calif.Lake Tahoe Tributary nearMeeks Bay, Calif.Blackwood Creek near Tahoe City,Calif.
Wood Creek near Crystal Bay,Nev.Trout Creek near Tahoe Valley,Calif.
Martis Creek near Truckee,Calif.
Alder Creek near Truckee,Calif.Prosser Creek near Boca, Calif.
Little Truckee River near HobartMills, Calif.Sagehen Creek near Truckee, Calif.
Galena Creek near Steamboat, Nev.
Long Valley Creek near HappyValley, Nev.
White River Tributary near Preston,Nev.
White River Tributary nearSunny side, Nev.
Pahragut Valley Tributarynear Hiko, Nev.
Muddy River Tributarynear Alamo, Nev.Fatterson Wash Tributarynear Pioche, Nev.Caselton Wash near Panaca, Nev.
Meadow Valley Wash Tributarynear Caliente, Nev.Meadow Valley Wash near Caliente,Nev.
Vernon Creek near Vernon, Utah
East Government Creek Tributarynear Vernon, UtahRush Valley Tributary nearFairfield, Utah
Clover Creek near Clover, Utah
Settlement Canyon near Tooele,Utah
South Willow Creek near Grantsville,Utah
Mack Canyon near Grantsville, Utah
North Fork Muskrat Canyon near
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Lati
tude , in decimal degrees
39.215
39.229
39.378
38.843
39.017
39.107
39.261
38.920
39.329
39.369
39.373
39.501
39.432
39.362
39.482
38.892
38.325
37.489
37.033
38.150
37.763
37.600
37.556
39.979
40.100
40.250
40.333
40.483
40.496
40.600
40.633
Longi
tude, in decimal degrees
119.207
119.228
119.317
120.024
120 . 126
120.161
119.956
119.971
120.117
120 . 182
120.131
120.276
120.237
119.827
119.619
115.194
115.045
115.336
114.981
114.586
114.429
114.658
114.564
112.379
112.550
112.200
112.533
112.283
112.574
112.583
112.633
System
atic Drainage years area, in of square
record miles
14
14
23
26
11
26
12
25
13
14
20
26
32
25
12
20
15
18
18
18
19
18
32
27
10
11
15
11
26
12
11
5.
0.
4.
33.
0.
11.
1,
36,
39,
7.
52.
36,
10,
8.
82.
26.
20.
17.
2.
5.
70.
0.
1,670.
25.
0.
0.
4.
5.
4.
2.
1.
.75
.12
.39
.10
.64
.20
.69
.70
.90
.47
.90
.50
.50
.50
,60
.0
.00
.00
00
00
20
50
00
00
98
26
45
77
19
84
78
Mean basin eleva
tion, in
feet
5,590
5,590
5,025
7,900
6,240
7,300
--
8,000
6,602
6,656
6,829
6,601
7,000
8,024
5,861
6,560
6,240
5,750
3,340
6,250
5,830
5,970
6,180
7,100
6,340
5,850
7,190
7,900
8,370
7,200
7,080
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
6.
6.
6.
40.
50.
68.
-
25.
34.
37.
45.
56.
45.
30.
8.
10.
10.
10.
6.
10.
6.
8.
7.
14.
_
-
-
_
33.
-
-
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
8
0
0
2
9
0
5
8
_
-
-
_
0
-
-
51.5
51.8
49.0
40.0
40.0
40.0
39.7
40.0
40.1
40.1
40.1
40.0
40.1
43.1
46.2
43.5
40.0
54.8
57.6
43.3
52.4
55.0
55.0
40.6
39.7
43.6
40.6
41.2
39.5
39.4
40.0Timpie, Utah
144 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10312012
10312015
10312050
10336600
10336635
10336660
10336693
10336780
10339400
10339900
10340500
10342000
10343500
10348900
10350100
09415480
09415560
09415600
09415800
09418100
09418150
09418450
09418500
10172700
10172720
10172740
10172760
10172790
10172800
10172810
10172830
Relation characteristic L H D 0 U
~
0
0
0
0
0
0
1
0
0
0
0
1
-
-
-
-
-
1
0
0
0
-
-
0
-
1
-
-
~
0
0
0
0
0
0
0
0
0
0
1
0
-
-
-
-
-
0
0
0
1
-
-
0
-
0
-
-
-
0
0
1
0
0
0
0
0
1
0
0
0
-
-
-
-
-
1
0
1
1
-
-
0
-
1
-
-
~
0
0
0
0
0
0
0
0
0
0
0
0
-
-
-
-
-
0
0
0
0
-
-
0
-
0
-
-
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
1
1
1
1
0
1
1
Peak discharge (cubic indicated recurrence
2
24
1
15698694
88
49749416
1541553923898786
62261996696011611696964549
0
0
0
0
0256221
00
4904482624
0
01411
03733
0
0
5
16
1
141,2401,210
1616
1,0601,030
3028
280274833793231221
1,3101,2702,3102,250
259254290282412398
125
105
97
25
35814808
22
1,2701,290
9191
9
33535
335958
20
14
10
194
8
1661,6701,610
2425
1,6001,520
4044
384410
1,2301,200
397382
2,0001,9503,8303,660
396394559542
1,2701,350
219
202
208
132
851,4501,410
55
2,0102,040
175175
30
155656
647574
48
37
feet per interval
25
435
19
4182,3002,190
3842
2,5002,320
53____
539600
1,8801,870
727687
3,2503,1306,8006,340
622620
1,2001,1304,1304,100
464
438
471
391
1852,6102,430
1519
3,2103,480
355357
65
349297
1249796
97
75
second) for (years)
50
716
33
7382,8302,670
5061
3,3503,060
63
672769
2,4602,5001,0901,0204,5204,33010,0009,180
833835
2,0201,8508,7108,160
821
771
825
656
3163,7903,640
3136
4,2804,750
561568
108
55125135
212115117
164
126
100
1,090
53
1,1903,4103,200
6685
4,3903,960
73
820961
3,1503,2601,5801,4506,1505,85014,50013,1001,0801,0903,3202,98016,90015,000
1,390
1,370
1,520
1,780
6715,2405,150
6370
5,5005,690
848856
283
173166181
421133138
363
298
Maximum peak discharge
of record (cubic feet per second)
1
1
920
2,550
43
2,100
40
535
1,880
730
4,560
7,910
765
4,730
2,560
219
600
162
77
49
1,710
26
2,400
825
6
49
87
155
92
2
1
Basin, Climatic, and Flood Characteristics 145
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10172835
10172870
10172885
10172890
10172895
10172900
10172902
10172905
10172909
10172913
10172920
10172925
10172940
10172970
10172990
10242420
10242460
10243240
10243660
10243700
10243950
10244220
10244240
10244360
10244460
10244480
10244490
10244620
10244720
10244745
10244950
Flood Station name region
Skull Valley Tributary near Delle,UtahTrout Creek near Callao, Utah
Great Salt Lake Desert Tributary No. 2near Dugway, UtahGovernment Creek near Dugway, Utah
Deep Creek near Ibapah, Utah
Bar Creek near Ibapah, Utah
Dead Cedar Wash near Wendover,Utah
Great Salt Lake Desert Tributarynear Delle, UtahBurnt Creek near Shores, Nev.
Loray Wash Tributary near Cobre,Nev.
Cotton Creek near Grouse Creek, Utah
Great Salt Lake Desert Tributary No. 3near Park Valley, UtahDove Creek near Park Valley, Utah
Rock Creek near Holbrook,Idaho
Blue Spring Creek near Snowville,UtahShoal Creek near Enterprise,Utah
Escalante Valley Tributary nearPanaca, Nev.
Baker Creek at Narrows, near Baker,Nev.
Connors Pass Creek near Shoshone,Nev.
Cleve Creek near Ely, Nev.
Mi Hick Canyon Tributary nearCurrie, Nev.
Maverick Canyon near Oasis, Nev.
Clover Valley Tributary nearArthur , Nev .
Dixie Valley Tributary nearEastgate, Nev.
Rawhide Flats Tributary nearSchurz, Nev.
Gabbs Valley Tributary nearGabbs, Nev.
Finger Rock Wash near Gabbs,Nev.
Teels Marsh Tributary at Basalt,Nev.
Franklin River near Arthur, Nev.
Overland Creek near Ruby Valley,Nev.
Steptoe Creek near Ely, Nev.
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Lati
tude, in decimal degrees
40
39
39
40
40
40
40
40
41
41
41
41
41
42
41
37
37
38
39
39
40
41
40
39
39
38
38
38
40
40
39
.683
.744
.867
.083
.250
.250
.417
.717
.560
.127
.785
.433
.792
.231
.850
.621
.736
.990
.043
.216
.225
.076
.560
.294
.144
.996
.689
.002
.824
.458
.201
Longi
tude, in decimal degrees
112
113
113
112
113
113
114
112
114
114
113
113
113
112
112
113
114
114
114
114
114
114
114
117
118
117
118
118
115
115
114
.917
.889
.117
.700
.983
.983
.189
.950
.493
.344
.841
.767
.565
.729
.450
.987
.139
.210
.633
.529
.436
.587
.961
.986
.749
.996
.017
.280
.136
.392
.687
System atic Drainage years area, in of square
record miles
12
28
12
11
10
15
18
11
17
18
10
12
15
18
14
13
18
23
19
29
12
11
16
26
16
13
11
16
19
22
20
1.50
8.80
5.48
59.00
460.00
12.00
5.00
0.97
10.50
24.00
19.10
10.10
33.20
44.00
78.00
19.00
7.90
16.40
0.45
31.80
1.40
3.02
3.00
11.00
0.96
7.00
207.00
1.07
10.30
9.00
11.10
Mean basin eleva
tion, in
feet
5,780
9,100
5,570
6,080
6,100
5,460
6,910
6,010
7,320
6,590
6,560
6,120
6,620
5,610
5,300
6,158
6,790
9,500
7,920
8,770
6,470
7,150
6,370
5,550
4,770
5,190
5,150
6,450
8,300
8,400
6,940
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
__
20.7
--
--
--
14.5
--
11.7
11.1
--
15.5
17.0
--
13.0
9.1
16.5
9.6
14.2
10.0
12.0
12.0
9.2
6.0
6.0
6.0
12.0
16.2
17.0
17.4
46.4
44.9
54.1
42.3
58.7
58.7
40.2
44.2
40.0
40.2
40.0
57.5
40.0
40.0
40.0
48.6
50.1
39.8
39.6
40.0
45.0
43.6
45.1
40.0
51.7
45.7
49.9
40.0
39.9
40.0
42.3
146 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10172835
10172870
10172885
10172890
10172895
10172900
10172902
10172905
10172909
10172913
10172920
10172925
10172940
10172970
10172990
10242420
10242460
10243240
10243660
10243700
10243950
10244220
10244240
10244360
10244460
10244480
10244490
10244620
10244720
10244745
10244950
Relation characteristic L H D 0 U
- - - - 1
10000
- - - - 1
- - - - 1
- - - - 1
11000
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
00000
11000
00000
10000
01000
- - - - 1
01000
- - - - 1
- - - - 1
10000
10100
- - - - 1
- - - - 1
- - - - 1
- - - - 1
10000
10000
00100
Peak discharge (cubic indicated recurrence
2
....
05045
0
0
07361
0
0
0
0
0
0
018215611091403232287062
04540
0
065
109
0
0
0
010591
109962421
5
....
148988
__._
40____
254
1,310368364
____
32
10
56
117.___
98....
62
1516106053503501081089695129128
48889
12__._
2118188181
- -
11----
51
773....
101421411491484242
10
....
46119118
109
412____
1,460850818
73
33____
105__._
207____
181
136
2521,1601,130
661658185186167164177174
13130131
37.___
503031
245243
____
47
141____
1,170
311671641751725758
feet per second) for interval (years)
25
....
103163159
--_.
249-_
905
3,2102,0601,830
150____
73
210-
438
384.___
299
5302,3402,1601,3301,350
335352300289247238
25201208
78----
1025262
815777
117
337
2,790 -
671981942082017986
50
____
173199199
427
1,630
6,0203,6503,350
256
120
365....
773
674
519
9423,6803,5002,1202,170
497529434427306304
41270284
130
1737387
1,8001,730
194
580
5,150 -
11022122623323497
109
100
____
435238242
_ -
917
2,520
7,1306,0705,840....
533
318
681 -
1,320
1,190
1,010
1,5505,5705,4503,2403,280
713751604608370373
114356368
324----
38199
1173,6903,620
539
1,220____
7,000
284243253259266117129
Maximum peak discharge
of record (cubic feet per second)
20
177
1,720
370
1,250
2,690
752
80
35
220
91
420
275
1,580
1,820
390
250
400
2
440
83
0
43
1,480
52
860
2,430
110
197
225
85
Basin, Climatic, and Flood Characteristics 147
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10245080
10245270
10245450
10245800
10245950
10246000
10246010
10246845
10246846
10246847
10247010
10247220
10247230
10247860
10248970
10248980
10249050
10249135
10249140
10249180
10249300
10249411
10249417
10249620
10249680
10249850
10249855
10249900
10325500
10326400
10326650
Flood Station name region
Nelson Creek Tributary nearCurrie, Nev.
Drylake Valley Tributary nearCaliente, Nev.Illipah Creek Tributary nearHamilton, Nev.
Newark Valley Tributary nearHamilton, Nev.
Bean Flat Tributary near Austin,Nev.
Garden Pass Creek Tributary nearEureka, Nev.Garden Pass Creek near Eureka,Nev.
Currant Creek Tributary nearCurrant, Nev.
Little Currant Creek near Currant,Nev.
Currant Creek below Little Currantnear Currant, Nev.Hot Creek Tributary near Warm Springs,Nev.
Black Rock Summit Tributary nearCurrent, Nev.
Railroad Valley Tributary nearCurrant, Nev.Penoyer Valley Tributary nearTempiute, Nev.
Stonewall Flat Tributary nearGoldfield, Nev.Lida Pass Tributary near Lida,Nev.
Sarcobatus Flat Tributary nearSpringdale, Nev.
San Antonio Wash Tributary nearTonopah, Nev.
Ralston Valley Tributary nearTonopah, Nev.
Saulsbury Wash near Tonopah, Nev.
South Twin River near RoundMountain, Nev.Campbell Creek Tributary nearEastgate, Nev.
Smith Creek Valley Tributarynear Austin, Nev.Big Smokey Valley Tributary nearTonopah, Nev.
Big Smokey Valley Tributary nearBlair Junction, Nev.Palmetto Wash Tributary nearLida, Nev.Palmetto Wash near Oasis, Calif.
Chiatovich Creek near Dyer, Nev.
Reese River near lone, Nev.
Reese River Tributary nearAustin, Nev.Silver Creek near Austin, Nev.
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
Lati
tude, in decimal degrees
40.
37.
39.
39.
39.
39.
39.
38,
38,
38,
38.
38.
38.
37.
37.
37.
37.
38.
38.
38.
38.
39.
39.
38.
38.
37.
37.
37.
38.
39.
39.
.300
.622
.360
.417
.492
.817
.779
.819
.847
.820
.200
.507
.543
.585
,594
,435
,222
327
290
,125
887
266
539
031
031
442
457
833
850
475
719
Longi
tude, in decimal degrees
114.772
114.773
115.351
115.631
116.533
116.164
116.106
115.326
115.367
115.345
116.217
115.889
115.798
115.680
117.210
117.557
117.126
117.124
117.100
116.808
117.244
117.699
117.474
117.231
117.710
117.690
117.769
118.203
117.467
117.319
117.168
System
atic Drainage years area, in of square
record miles
25
15
25
25
21
25
15
20
20
15
17
15
21
18
20
14
21
19
21
21
22
22
15
21
25
14
13
22
30
14
19
0
11
5
157
1
2
19
3
12
30
0
6
0
1
0,
1,
37.
3.
0.
56.
20.
2.
0.
2.
11.
4.
0.
37.
53.
8.
25.
.70
.00
.47
.00
.10
.12
.20
.13
.90
.00
.77
.35
.37
.48
.53
.59
.10
.42
,20
.00
,00
,14
63
39
40
73
24
30
00
27
00
Mean basin eleva
tion, in
feet
6,000
5,910
7,100
6,920
6,400
7,010
6,510
6,970
8,280
7,850
5,300
6,300
5,200
5,680
5,630
7,990
5,140
6,920
5,980
6,810
9,130
7,450
6,440
6,100
5,440
7,440
6,090
9,960
8,800
6,590
7,120
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
8.0
7.5
12.0
10.3
10.0
10.0
10.1
10.0
13.5
13.7
6.0
10.1
8.0
8.0
6.0
12.0
7.7
8.9
6.0
12.0
15.4
16.0
10.0
6.0
6.0
6.0
8.0
17.5
19.0
12.0
14.0
44.8
55.0
52.4
49.6
38.7
39.9
39.8
52.7
55.3
54.1
42.9
40.0
43.4
55.1
52.9
49.9
55.1
39.0
45.0
41.4
40.0
39.6
40.0
50.7
49.6
49.4
47.5
38.8
40.0
40.0
40.3
148 Methods for Estimating Magnituds and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10245080
10245270
10245450
10245800
10245950
10246000
10246010
10246845
10246846
10246847
10247010
10247220
10247230
10247860
10248970
10248980
10249050
10249135
10249140
10249180
10249300
10249411
10249417
10249620
10249680
10249850
10249855
10249900
10325500
10326400
10326650
Relation characteristic L H D 0 U
- - - - 1
- - - - 1
11100
00100
- - - - 1
- - - - 1
10100
10100
01000
10000
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
10000
- - - - 1
- - - - 1
- - - - 1
01000
00100
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
11000
00000
- - - - 1
00100
Peak discharge (cubic indicated recurrence
2
--__
0
011102926
----
0
0211832
21181916
0
0
0
0
0
032
0
0
0423722
0
0
0
0
024227971
065
5
....
7____
675454
114118
____
10____
16113113141459597778
9
42____
5
14
6____
121618
24____
3
22696961010
____
6____
19____
73 -
29____
35555
216216
____
502627
10
....
27____
152130128228239
32____
422652613334
104104163164
-_--
35
98____
23____
47____
25____
283951
.___
57____
12
3321531522525
____
23____
56____
177 ~
62____
148789
369365
____
1075358
feet per second) for interval (years)
25
....
60
339349331467540
____
69----
856486118588
190189371368
____
82____
211____
54
106
57
5491
185
118____
28 _
6912562507171
____
48____
123____
413.___
124____
30149159659638
____
226111143
50
....
98____
589673646734838
____
114____
1441,1401,090
159161283286636634
135
363____
88
177
94
91154274
____
200-
44
1,240364363143142
____
79 -
208
718
212....
48216232961947
....
391175217
100
....
271
1,1401,2301,2101,0901,150____
294____
3331,9001,870281286406412
1,0401,040
378____
745
272____
450
272
213242339
____
438____
144____
1,890504506276277
218____
487
1,410 -
437____
151306318
1,3501,340____
768258293
Maximum peak discharge
of record (cubic feet per second)
52
156
1,120
291
21
190
650
99
366
404
100
200
10
130
150
1
63
660
48
340
510
179
130
10
460
193
30
527
1,000
80
52
Basin, Climatic, and Flood Characteristics 149
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10326850
10351850
10173450
10174500
10174800
10185000
10187300
10194999
10205030
10205070
10205700
10208500
10210000
10211000
10215700
10215900
10216300
10216400
10219200
10220300
10224100
10232500
10233000
10233500
10234500
10235000
10236000
10236500
10237500
10240600
10241300
Flood Station name region
Reese River Tributary nearBattle Mountain, Nev.Pyramid Lake Tributary nearNixon , Nev .
Mammoth Creek above West Hatch Ditchnear Hatch, UtahSevier River at Hatch, Utah
Red Canyon Tributary near BryceCanyon, Utah
Antimony Creek near Antimony, Utah
Otter Creek near Koosharem,Utah
Clear Creek (composite) nearSevier, Utah
Salina Creek near Emery, Utah
Cottonwood Creek near Salina, Utah
Salina Creek above Diversion nearSalina, Utah
Oak Creek near Fairview, Utah
Pleasant Creek near Mount Pleasant,Utah
Twin Creek near Mount Pleasant,Utah
Oak Creek near Spring City, Utah
Manti Creek below Dugway Creek,near Manti, UtahSixmile Creek near Sterling,Utah
Twelvemile Creek near Mayfield,Utah
Chicken Creek near Levan, Utah
Tintic Wash Tributary near Nephi,Utah
Oak Creek above Little Creeknear Oak City, UtahChalk Creek near Fillmore, Utah
Meadow Creek near Meadow, Utah
Corn Creek near Kanosh, Utah
Beaver River near Beaver,UtahSouth Creek near Beaver, Utah
North Fork North Creek nearBeaver, Utah
South Fork North Creek near Beaver,UtahIndian Creek near Beaver, Utah
Big Wash near Milford, Utah
Fremont Wash near Paragonah,
6
6
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
Lati
tude , in decimal degrees
40
39
37
37
37
38
38
38
38
38
38
39
39
39
39
39
39
39
39
39
39
38
38
38
38
38
38
38
38
38
38
.542
.858
.622
.651
.733
.101
.611
.581
.912
.917
.933
.674
.543
.492
.448
.259
.200
.101
.552
.667
.356
.964
.891
.774
.281
.190
.346
.339
.431
.483
.083
Longi
tude, in decimal degrees
117.050
119.476
112.519
112.429
112.283
111.882
111.811
112.274
111.530
111.700
111.817
111.408
111.383
111.407
111.425
111.579
111.667
111.646
111.829
112.083
112.232
112.307
112.327
112.399
112.574
112.552
112.551
112.387
112.587
113.117
112.683
System
atic Drainage years area, in of square
record miles
20
18
22
62
12
21
18
60
23
10
16
22
21
12
17
18
16
21
24
14
21
29
11
17
73
12
18
11
13
10
16
0
1
105
340
2
50
23
166
51
7
280
11
16
5
8
26
29
59
27
18
5
58
11
68
91
15
14
23
18
51
120
.20
.94
.00
.00
.20
.30
.50
.00
.80
.80
.00
.80
.40
.90
.00
.40
.00
.40
.90
.00
.58
.70
.60
.0
.00
.00
.10
.00
.50
.00
.00
Mean basin eleva
tion, in
feet
5,200
5,000
8,996
8,480
7,860
9,560
9,580
7,880
8,720
7,470
7,950
7,560
8,830
8,900
9,140
9,080
8,703
8,570
7,480
6,070
7,710
8,020
8,380
7,400
9,280
8,730
8,340
9,370
8,370
6,120
7,240
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
8.0
7.0
24.2
22.5
--
21.6
22.6
20.9
25.3
_-
24.0
28.0
30.0
29.0
26.1
32.4
26.1
20.6
25.0
24.0
24.0
24.7
27.7
--
25.5
26.0
24.0
--
44.3
44.0
40.0
40.0
40.0
43.7
39.9
43.2
40.0
40.5
42.4
39.8
40.1
40.1
40.0
39.9
40.5
40.1
45.1
40.8
40.9
48.6
46.3
43.6
41.1
40.3
40.2
39.7
40.0
59.1
39.9Utah
150 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10326850
10351850
10173450
10174500
10174800
10185000
10187300
10194999
10205030
10205070
10205700
10208500
10210000
10211000
10215700
10215900
10216300
10216400
10219200
10220300
10224100
10232500
10233000
10233500
10234500
10235000
10236000
10236500
10237500
10240600
10241300
Relation characteristic L H D 0 U
0
-
1
1
-
1
1
1
1
1
1
1
0
0
0
1
0
0
0
1
1
0
1
1
0
0
1
0
1
1
1
0
-
0
0
-
0
0
0
0
1
1
1
1
1
0
0
0
1
0
1
0
1
1
0
0
0
0
0
1
0
0
0
-
0
0
-
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
1
0
0
0
0
0
1
0
-
0
0
-
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
11
0451450629629
182502505860
2362371931932727
5565561661651581576767
115114367364220219264264697063632627
2372375959
14514537637631323940
1641642829168166105107
5
66
19573576900905
473833897795
38539135535710199
9309233062963323231321301771744654504284144694641761771601535456
42542199
10535234963463478907582
4604386982
331310200219
10
1313
68651670
1,0901,100
8248149889
136497512490494208193
1,2501,220
4354105104821941902212205315116175806486352852852622437885
587577131151571552811810130159106126801711115147468422276325
feet per second) for interval (years)
25
3132
164748782
1,3301,350
173615627104182654690691691459409
1,7301,670
648598836761300291281286617596921835931896472481445443116142838823178231974933
1,0301,020228276156204
1,4701,180
203265671676384522
50
5454
276819878
1,5101,530
249722746115231782827865863776649
2,1602,030
850778
1,1701,050
402391328348681675
1,2001,0701.1901,130
653656630612149191
1,0601,040
218302
1,3901,2901,2001,190
330390200271
2,1901,680298377844845472648
100
8993
692889975
1,7001,720
346834873127284918971
1,0601,0501,260
9972,6502,4401,1001,0001,6101,410
529515377418747763
1,5301,3501,4901,400
872864864821187249
1,3201,280263382
1,9201,7201,3501,340
464530252349
3,1502,340
426515
1,0301,030
567777
Maximum peak discharge
of record (cubic feet per second)
26
950
838
3,000
365
669
117
769
621
457
2,300
1,190
2,060
488
300
682
1,050
1,350
390
545
120
1,850
198
1,350
1,080
200
198
1,550
311
520
282
Basin, Climatic, and Flood Characteristica 151
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10241400
10241470
09166500
09168100
09172500
09174500
09175500
09175900
09177000
09181000
09182000
09182600
09183000
09184000
09185200
09185500
09186500
09187000
09313000
09313500
09314200
09314280
09314400
09314500
09315150
09315200
09315400
09315500
09315900
09316000
09318000
Station name
Little Creek near Partagonah,Utah
Center Creek above Farowan Creek,near Parowan, UtahDolores River at Dolores, Colo.
Disappointment Creek near DoveCreek, Colo.San Miguel River near Placerville,Colo.
Cottonwood Creek near Nuela, Colo.
San Miguel River at Naturita,Colo.Dry Creek near Naturita, Colo.
San Miguel River at Uravan, Colo.
Onion Creek near Moab, Utah
Castle Creek above Diversionsnear Moab, UtahSalt Wash near Thompson, Utah
Courthouse Wash near Moab, Utah
Mill Creek near Moab, Utah
Kane Springs Canyon near Moab,Utah
Hatch Wash near La Sal, Utah
Indian Creek above CottonwoodCreek near Monti cello, UtahCottonwood Creek near Monticello,Utah
Price River near Heiner, Utah
Price River near Helper, Utah
Miller Creek near Price, Utah
Desert Seep Wash near Wellington,Utah
Coleman Wash near Woodside, Utah
Price River at Woodside, Utah
Saleratus Wash Tributary nearWoodside, UtahSaleratus Wash Tributary No. 2near Woodside, UtahSaleratus Wash above Creek Washnear Green River, Utah
Saleratus Wash at Green River,Utah
Browns Wash Tributary near GreenRiver, UtahBrowns Wash near Green River, Utah
Huntington Creek near Huntington,
Flood region
7
7
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Lati
tude, in decimal degrees
37,
37,
37,
37.
38,
38,
38,
38,
38,
38
38
38
38,
38
38
38
37
38,
39
39
39,
39,
39
39
39
39,
39,
38
38,
38,
39,
.906
,793
,472
,877
.035
.274
.218
.092
.357
.725
.593
.953
.613
.562
.400
.243
.975
.062
.719
.651
.505
.421
.383
.264
.133
.100
.017
.981
.983
.986
.371
Longi
tude, in decimal degrees
112.708
112.815
108.497
108.582
108.121
108.362
108.566
108.621
108.712
109.344
109.265
109.658
109.579
109.513
109.450
109.439
109.518
109.574
110.865
110.857
110.675
110.646
110.400
110.346
110.333
110.317
110.300
110.246
110.100
110.129
111.063
System
atic Drainage years area, in of square
record miles
21
22
72
29
49
10
53
12
23
13
24
15
28
40
15
22
22
17
37
28
13
15
10
43
15
15
10
22
15
19
71
15
11
5
147
308
38
1,069
78
1,499
18
7
3
162
74
17
378
31
115
415
530
62
191
3
1,540
10
4
120
180
3
75
190
.80
.60
.00
.00
.00
.80
.00
.60
.00
.80
.58
.90
.00
.90
.80
.00
.20
.00
.00
.00
.00
.00
.60
.00
.00
.40
.00
.00
.89
.00
.00
Mean basin eleva
tion, in
feet
7,470
8,450
99,800
8,000
10,200
7,700
9,000
7,400
8,400
5,702
9,480
5,508
4,810
7,170
6,620
6,550
8,590
7,210
8,160
7,920
7,040
5,813
5,540
6,490
5,070
5,030
5,430
5,050
4,300
5,220
9,000
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
21.0
22.0
30.0
22.0
25.0
17.0
24.0
18.0
22.0
12.3
24.7
10.1
7.5
16.7
15.9
13.1
21.2
17.9
19.8
19.4
14.8
7.8
13.7
7.6
7.7
7.9
7.5
6.9
9.3
22.7
43.9
41.5
46.1
45.1
42.1
44.5
45.9
45.2
45.6
50.6
45.9
40.0
53.7
55.7
51.0
51.9
46.3
51.1
37.3
45.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.5
40.0
40.0
40.0Utah
152 Methods for Estimating Msgnitude snd Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10241400
10241470
09166500
09168100
09172500
09174500
09175500
09175900
09177000
09181000
09182000
09182600
09183000
09184000
09185200
09185500
09186500
09187000
09313000
09313500
09314200
09314280
09314400
09314500
09315150
09315200
09315400
09315500
09315900
09316000
09318000
Relation characteristic L H D 0 U
1
0
1
0
0
0
1-
0
1
1
0
0
0
1
1
0
0
0
0
0
1
0
1
0
1
-
1
1
0
0
0
0
0
0
1
0
0
-
0
1
0
0
0
0
0
0
1
0
1
0
0
1
0
0
0
0
-
1
0
0
0
1
0
0
0
0
0
1
-
0
0
1
0
1
0
0
0
0
1
0
0
0
0
0
1
1
1-
0
0
1
0
0
0
0
0
0
1
0
-
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
Peak discharge (cubic indicated recurrence
2
37375555
3,4003,3901,1801,1801,3701,370
123135
2,7702,770
6913,7103,690
9359211012
275273
2,2002,190
694694540536503523134138390400
1,1401,1401,8801,8801,4301,410
534554256254
4,5404,530
805794
1,0601,040
1,1702,4902,470
205206
1,7901,770
812812
5
134134137138
5,1005,0502,5702,5301,9501,950
236326
4,4504,430
1,4405,6705,6101,2801,260
1837
723708
4,6704,6101,8301,820
829831
1,2001,330
381404
1,2701,3102,1702,1903,9903,9503,4103,220
8601,030
608598
6,4806,4802,2402,1302,4202,270
2,5804,5604,490
612623
3,7503,6501,3001,310
10
261255225225
6,2706,1503,9003,7702,3302,330
327577
5,6205,580
2,0607,0006,8901,5201,540
2681
1,1901,1407,0606,8803,0803,0201,0401,0801,9202,250
683735
2,3302,3603,1403,1805,9505,7905,2304,6401,1301,630
944919
7,7507,8103,8203,4403,6303,210
3,8006,3906,2301,0901,1105,4605,1701,6401,670
feet per interval
25
531509391385
7,7907,5406,1205,7102,8102,860
4581,0707,1607,110
3,0908,7008,6401,8402,050
36184
2,0001,850
11,10010,6005,4105,1401,3301,5103,2503,9901,3101,3904,4104,2504,7504,8109,1608,6508,1006,6001,5302,8101,5001,4609,3209,6706,7005,5505,4904,490
5,8109,3208,9802,0102,0308,0907,4202,0702,160
second) for (years)
50
839778565548
8,9508,6208,2207,4703,1603,300
5641,5508,3208,310
4,0309,97010,1002,1002,590
45296
2,7802,51015,00014,0007,8407,2601,5501,9204,6005,7002,0202,0706,6406,1006,2906,35012,10011,20010,6008,1801,8703,9902,0101,96010,50011,3009,6307,5007,1105,540
7,65012,00011,5002,9902,95010,4009,3802,4002,570
100
1,2701,150
791755
10,1009,68010,8009,5403,5203,760
6782,0909,5009,550
5,01011,20011,6002,3603,220
55430
3,7403,30019,80018,10011,0009,9001,7902,4106,3407,7203,0202,9509,5708,3208,1708,14015,60014,00013,5009,9402,2705,3302,6102,55011,60012,90013,3009,8208,9106,700
9,61015,20014,4004,2904,11012,90011,5002,7203,000
Maximum peak discharge
of record (cubic feet per second)
351
353
10,000
8,140
10,000
321
7,100
5,660
8,910
2,100
27
1,380
12,300
5,110
1,290
4,650
2,330
2,200
9,340
12,000
5,000
2,060
1,040
9,720
5,340
3,720
19,500
14,200
1,470
5,620
2,500
Basin, Climatic, and Flood Characteristics 153
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09324500
09326500
09327600
09328050
09328300
09328500
09328600
09328700
09328720
09328900
09329900
09330120
09330200
09330300
09330400
09330500
09331500
09333900
09334000
09334400
09334500
09336400
09337000
09337500
09338900
09339200
09342500
09343500
09345500
09346000
09346200
Flood Station name region
Cottonwood Creek near Orangeville,Utah
Ferron Creek (upper station) nearFerron, Utah
Ferron Creek Tributary near Ferron,Utah
Dry Wash near Moore, Utah
Sids Draw near Castle Dale, Utah
San Rafael River near Green River,Utah
Georges Draw near Hanksville, Utah
Temple Wash near Hanksville, Utah
Old Woman Wash near Hanksville,Utah
Crescent Wash near Crescent Junction,Utah
Fine Creek near Bicknell, Utah
Sulphur Creek near Fruita, Utah
Pleasant Creek at Notom, Utah
Neilson Wash near Caineville, Utah
Fremont River near Hanksville,Utah
Muddy Creek near Emery, Utah
Ivie Creek above diversions nearEmery, Utah
Butler Canyon near Hite, Utah
North Wash near Hanksville (Hite),UtahFry Canyon near Hite, Utah
White Canyon near Hanksville, Utah
Upper Valley Creek near Escalante,UtahFine Creek near Escalante, Utah
Escalante River near Escalante,Utah
Deer Creek near Boulder, Utah
Twentymile Wash near Escalante,Utah
San Juan River at Pagosa Springs,Colo.
Rito Blanco near Fagosa Springs,Colo.
Little Navajo River at Chromo,Colo.Navajo River at Edith, Colo.
Rio Amargo at Dulce, N. Mex.
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Lati
tude, in decimal degrees
39
39
39
38
38
38
38
38
38
38
38
38
38,
38,
38,
38,
38.
38.
37.
37.
37.
37.
37.
37.
37.
37.
37.
37.
37.
37.
36.
.267
.104
.067
.933
.983
.858
.817
.650
.683
.942
.269
.300
.233
.367
.367
.982
,758
,000
.899
.617
.799
733
862
,778
850
567
266
194
046
003
933
Longi
tude , in decimal degrees
111.129
111.213
111.033
111.067
110.667
110.369
110.700
110.550
110.533
109.821
111.583
111.267
111.117
110.883
110.750
111.249
111.421
110.500
110.449
110.133
110.376
111.717
111.635
111.574
111.350
111.367
107.010
106.905
106.842
106.907
107.000
System
atic Drainage years area, in of square
record miles
52
51
12
15
15
50
14
10
10
10
16
16
14
15
15
43
24
16
21
15
20
16
34
31
16
10
56
18
17
36
30
208
138
0
14
17
1,628
6
38
17
23
104
56
80
22
1,900
105
50,
14
136
20
276,
53,
68,
320,
63.
140.
298.
23.
21.
172.
168.
.00
.00
.96
.00
.60
.00
.63
.20
.60
.30
.00
.70
.60
.30
.00
.00
.00
.70
.00
.90
.00
.00
.10
.00
,00
,00
,00
30
90
00
00
Mean basin eleva
tion, in
feet
8,940
8,800
6,300
6,320
6,380
6,910
7,010
5,630
5,450
6,180
9,300
7,400
7,980
4,830
7,450
8,850
8,870
5,150
5,400
6,250
6,090
7,620
8,890
8,030
7,680
6,170
9,700
9,400
8,900
9,200
7,930
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
21.2
22.7
7.6
7.4
9.1
12.9
11.0
8.6
8.2
12.7
20.3
14.7
17.0
7.0
13.7
24.5
20.3
7.3
10.0
13.0
13.0
18.2
22.7
18.4
15.4
13.5
36.0
34.0
26.0
33.0
17.7
39.9
39.9
40.0
40.0
39.6
45.1
39.0
39.3
39.2
39.9
40.9
39.9
39.6
49.9
56.0
40.0
40.1
54.4
55.2
50.2
55.4
39.9
40.0
39.7
39.9
47.3
41.2
41.6
38.4
40.2
42.4
154 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES- -Continued
Station number
09324500
09326500
09327600
09328050
09328300
09328500
09328600
09328700
09328720
09328900
09329900
09330120
09330200
09330300
09330400
09330500
09331500
09333900
09334000
09334400
09334500
09336400
09337000
09337500
09338900
09339200
09342500
09343500
09345500
09346000
09346200
Relation characteristic L H D 0 U
0
0
0
1
1
1
1
-
1
1
0
0
0
1
0
1
1
1
0
1
0
0
1
1
1
1
0
0
0
0
0
1
0
0
0
0
0
0
-
0
1
0
0
0
1
0
0
0
1
0
1
0
1
0
0
0
0
1
0
0
0
0
0
0
0
1
1
1
0
-
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
1,2901,290
903902111110324324459457
2,2202,230
210210
6362862924484487487
524525256266
1,1301,1204,3004,280
575576190194409410
1,1801,180
634629
2,1902,180
718714169173782788361366
1,7501,7302,6602,650
190192145148850850
1,0101,010
5
2,0802,0701,5001,500
342332643657
1,2001,1703,9804,040
592584
1,470860887
1,1101,100
232308
1,2201,220
815859
2,2802,2107,3307,2201,2001,200
395423748773
3,0703,0501,2901,2704,2504, 1901,5801,550
370396
1,7401,7701,1801,1902,9402,8704,4804,420
313334253281
1,3101,3201,5601,570
10
2,6702,6601,9801,980
607566938986
1,9401,8405,5505,7001,030
987
2,2201,5201,5501,8401,780
422615
1,8801,8701,4601,5303,2903,1109,6509,3701,7401,750
583662
1,0301,1305,0204,9001,9401,8705,9905,8202,4402,320
568641
2,5902,6502,1702,1103,8803,7706,1305,950
403469335420
1,6601,6901,9402,000
feet per interval
25
3,4903,4902,6602,6901,110
9711,4201,5603,1802,8908,1108,4501,8601,690
3,4702,7502,7203,2702,990
7991,2202,9602,9002,6802,7104,8504,49012,90012,4002,5902,600
8871,0901,4501,7708,4207,9603,0602,8708,6108,2303,9503,590
9101,0903,9004,0404,1603,7805,2305,1908,8408,370
524710451682
2,1702,2902,4602,660
second) for (years)
50
4,1504,1803,2303,3101,6301,3601,8802,1304,3403,84010,50011,0002,7402,370
4,6304,0303,8504,8004,1601,2101,8303,9503,8203,9303,8206,2305,74015,50014,9003,3403,3501,1701,5001,8102,40011,70010,8004,1703,82010,90010,3005,4504,7701,2401,5305,0405,2506,3205,4206,3506,490
11,40010,600
619945545940
2,5902,8202,8603,260
100
4,8504,9303,8503,9802,2901,8302,4302,7905,7004,90013,30014,0003,8903,200
5,9005,6605,1706,8605,5901,7502,5305,1004,8505,5205,1107,8007,170
18,30017,6004,1904,1901,4901,9602,2103,14015,80014,1005,5604,96013,40012,6007,3406,1601,6602,0606,3206,5909,2007,4207,5807,930
14,50013,200
7171,210
6451,2303,0603,4103,2703,910
Maximum peak discharge
of record (cubic feet per second)
7,220
4,180
600
1,630
2,150
12,000
1,650
1,880
2,650
4,160
707
2,600
2,040
5,450
15,300
3,340
1,240
1,950
8,900
3,500
7,390
5,560
1,010
3,450
3,820
4,620
25,000
475
399
2,840
2,860
Baain, Climatic, and Flood Characteristics 155
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09346400
09349500
09349800
09350500
09350800
09355000
09355700
09356400
09356520
09357200
09361000
09361500
09362000
09363000
09363100
09363500
09364500
09366500
09367400
09367530
09367840
09367860
09367880
09367900
09368500
09369000
09371000
09372000
09372200
09378630
09378700
Flood Station name region
San Juan River near Carracas, N. Mex.
Piedra River near Piedra, Colo.
Piedra River near Arboles, Colo.
San Juan River at Rosa, N. Hex.
Vaqueros Canyon near Gobernador,N. Mex.
Spring Creek at La Boca, Colo.
Gobernador Canyon near Gobernador,N. Hex.
Manzanares Canyon near Turley,N. Hex.
Burro Canyon near Lindrith,N. Hex.
Gallegos Canyon Tributary nearNageezi, N. Mex.Hermosa Creek near Hermosa, Colo.
Animas River at Durango, Colo.
Lightner Creek near Durango,Colo.
Florida River near Durango, Colo.
Salt Creek near Oxford, Colo.
Animas River near Cedar Hill,N. Mex.
Animas River at Farmington,N. Mex.La Plata River at Colorado-New Mexico State line
La Plata River Tributary nearFarmington, N. Mex.Locke Arroyo near Kirtland, N. Mex.
Yazzie Wash near Mexican Springs,N. Mex.Chusca Wash near Mexican Springs,N. Mex.
Catron Wash near Mexican Springs,N. Mex.Black Springs Wash near MexicanSprings, N. Mex.
West Mane os River near Mancos, Colo.
East Mancos River near Mancos, Colo.
Mancos River near Towaoc, Colo.
McElmo Creek near Colorado-Utah State line
McElmo Creek near Bluff, Utah
Recapture Creek near Blanding,UtahCottonwood Wash near Blanding,
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Lati
tude , in decimal degrees
37.014
37.222
37.088
37.006
36.733
37.011
36.685
36.737
36.272
36.467
37.422
37.279
37.604
37.325
37.140
37.038
36.720
37.000
36.786
36.733
35.844
35.811
35.771
35.761
37.382
37.370
37.027
37.324
37.217
37.756
37.561
Longi
tude, in decimal degrees
107
107
107
107
107
107
107
107
107
107
107
107
107
107
107
107
108
108
108
108
108
108
108
108
108
108
108
109
109
109
109
.312
.342
.397
.403
.283
.596
.419
.704
.246
.917
.844
.880
.893
.748
.753
.874
.202
.188
.225
.300
.883
.847
.828
.817
.257
.231
.741
.015
.183
.476
.578
System
atic Drainage years area, in of square
record miles
25
34
24
43
31
36
30
30
14
35
50
63
22
45
23
52
73
66
17
35
37
29
18
34
16
15
53
36
13
21
28
1230
371
629
1,990
60
58
19
3
9
0
172
692
66
96
17
1,090
1,360
331
1
2
2
8
26
7
39
11
526
346
720
3
205
.00
.00
.00
.00
.50
.00
.80
.20
.11
.20
.00
.00
.00
.00
.70
.00
.00
.00
.03
.96
.10
.70
.90
.05
.40
.90
.00
.00
.00
.77
.00
Mean basin eleva
tion, in
feet
8,500
9,400
8,300
9,800
7,500
7,300
6,900
7,000
6,965
6,750
9,600
10,200
8,400
9,900
6,800
9,300
9,500
7,712
5,380
5,500
7,400
6,800
6,600
5,916
9,300
9,700
7,200
6,300
6,200
8,880
6,820
Mean annual precipi tation,
in inches
30.0
33.0
27.0
27.0
15.0
12.0
12.1
10.6
11.1
34.0
30.0
22.0
38.0
18.0
30.0
29.0
35.0
--
8.0
16.0
14.0
13.0
12.8
30.0
30.0
16.0
10.5
10.3
22.9
16.4
Mean annual
evapor
ation, in
inches
48.4
43.5
47.4
49.5
51.5
50.7
53.4
55.1
51.2
54.6
40.2
43.0
35.0
40.9
48.9
51.6
55.1
52.5
54.9
55.3
50.0
50.0
50.0
50.0
43.0
42.8
55.6
55.1
59.8
44.8
47.3Utah
156 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09346400
09349500
09349800
09350500
09350800
09355000
09355700
09356400
09356520
09357200
09361000
09361500
09362000
09363000
09363100
09363500
09364500
09366500
09367400
09367530
09367840
09367860
09367880
09367900
09368500
09369000
09371000
09372000
09372200
09378630
09378700
Relation characteristic L H D 0 U
0
0
0
0
0
-
-
-
-
0
1
1
0
0
0
0
0
0
1
0
1
1
1
-
0
-
-
0
0
0
1
0
0
0
0
0
-
-
-
-
0
0
1
0
0
0
0
1
0
0
0
0
0
0
-
0
-
-
0
1
0
1
0
0
0
0
0
-
-
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
-
-
0
0
0
0
0
0
0
0
0
-
-
-
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
-
-
0
0
1
0
0
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
1
0
0
0
0
Peak discharge (cubic indicated recurrence
2
4,1104,0902,0802,0702,4702,4606,7306,700
205210
602-
372
147
250133132986985
4,9304,910
484485985982214216
5,7705,7406,0706,050
7627659292
105106284282
1,1201,1101,7201,700
260316318
204
1,8409589666517021719
1,0801,080
5
6,2606,1503,4703,4204,2604,200
10,60010,400
518549
1,270
845
366
589255250
1,6901,6807,4207,320
971980
1,4801,470
392416
8,1308,0109,0308,9301,5801,600
253257254262591580
2,4202,3403,0402,900
647584600
435
3,4901,5401,6101,8002,090
4358
2,8202,800
10
7,7407,5004,6504,5105,6905,540
13,70013,200
866946
1,850
1,260
571
897358345
2,2302,2209,4509,1801,4101,4301,8401,820
535612
9,7909,520
11,10010,9002,3202,370
435446403431863833
3,6203,3804,0703,720
1,010808855
632
4,8002,0002,2103,2003,850
69113
4,8004,680
feet per interval
25
9,6409,2806,4406,1107,7607,440
18,10016,9001,5301,710
2,790
1,970
924
1,420511485
3,0002,99012,50011,9002,1002,1602,3602,340
742968
12,00011,50013,80013,3003,5103,640
778799657741
1,2901,2205,5304,8805,5404,810
1,6301,1401,270
965
6,9202,6403,2306,1707,250
114233
8,6508,080
second) for (years)
50
11,10010,7008,0407,5109,5009,050
21,90020,0002,2402,500
3,650
2,620
1,260
1,910642609
3,6203,630
15,20014,2002,7402,8302,7802,780
9131,320
13,70013,00015,90015,2004,5904,8001,1401,160
9011,0501,6601,5507,2606,1706,7505,700
2,2201,4301,660
1,270
8,8103,1804,2109,61010,700
159361
12,80011,500
100
12,50012,2009,8809,080
11,40010,80026,00023,3003,1903,480____
4,570
3,330
1,640
2,450787750
4,2804,310
18,20016,7003,4703,5803,2203,2501,1001,720
15,40014,50018,00017,1005,8506,1201,6001,6101,2001,4402,0901,9309,2607,6208,0506,680
2,8801,7602,100
1,600
10,7003,7705,320
14,50014,800
215515
18,40015,900
Maximum peak discharge
of record (cubic feet per second)
9,730
7,980
8,370
25,000
2,520
1,980
3,450
2,210
725
580
2,980
25,000
1,850
3,200
811
13,100
25,000
4,750
1,130
812
1,390
6,400
4,750
2,200
1,080
642
5,300
3,040
13,100
142
20,500
Basin, Climatic, and Flood Characteristics 157
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09378950
09379000
09379030
09379060
09379100
09379300
09379560
09379800
09379820
09379980
09381100
09381500
09381800
09382000
09383020
09403000
09403500
09403600
09403700
09403750
09403780
09403800
09404450
09404500
09405420
09405500
09406000
09406300
09406700
09406800
09408000
Flood Station name region
Comb Wash near Blanding, Utah
Comb Wash near Bluff, Utah
Black Mountain Wash near Chinle,Ariz.Lukachukai Creek Tributary nearLukachukai, Ariz.
Long House Wash near Kayenta, Ariz.
Lime Creek near Mexican Hat, Utah
El Capitan Wash near Kayenta,Ariz.
Coyote Creek near Kanab, Utah
Buck Tank Draw near Kanab, Utah
Jack Bench Wash Tributary nearPage, Ariz.
Henrieville Creek at Henrieville,UtahParia River near Cannonville, Utah
Faria River near Kanab, Utah
Faria River at Lees Ferry, Ariz.
House Rock Wash Tributarynear Marble Canyon, Ariz,
Bright Angel Creek near GrandCanyon, Ariz.
Kanab Creek near Glendale, Utah
Kanab Creek near Kanab, Utah
Johnson Wash near Kanab, Utah
Sagebrush Draw near Fredonia, Ariz.
Kanab Creek near Fredonia, Ariz.
Bitter Seeps Wash Tributary nearFredonia, Ariz.
East Fork Virgin River nearGlendale, UtahMineral Gulch near Mt. Carmel, Utah
North Fork Virgin River below BullockCanyon, near Glendale, Utah
North Fork Virgin River nearSpringdale, Utah
Virgin River near Virgin, Utah
Kanarra Creek at Kanarraville,Utah
South Ash Creek below Mill Creeknear Pintura, UtahSouth Ash Creek near Pintura, Utah
Leeds Creek near Leeds, Utah
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Lati
tude, in decimal degrees
37
37
36
36
36
37
36
37
37
36
37
37
37
36
36
36
37
37
37
36
36
36
37
37
37
37
37
37
37.
37,
37.
.550
.266
.333
.469
.567
.217
.859
.133
.083
.714
.567
.481
.067
.872
.701
.100
.283
.101
.033
.901
.864
.857
.339
.233
.418
.210
.198
.538
.364
.331
.267
Longi
tude, in decimal degrees
109.667
109.675
109.624
109.406
110.488
109.817
110.265
111.750
111.700
111.592
111.983
112.021
111.883
111.594
111.929
112.093
112.483
112.547
112.350
112.376
112.579
112.758
112.604
112.733
112.800
112.978
113.206
113.168
113.334
113.281
113.370
System
atic Drainage years area, in of square
record miles
10
10
15
14
15
15
14
14
10
15
16
21
15
63
13
50
16
18
16
15
16
14
20
14
11
63
70
23
16
14
23
10
280
80
1
1
67
5
89
5
0
34
220
668
1,410
3
101
72.
198.
237,
0,
1,085,
2.
69.
7.
29.
344.
934.
9.
11.
14.
15.
.30
.00
.70
.37
.38
.20
.88
.00
.25
.98
.00
.00
.00
.00
.54
.00
.00
,00
,00
,68
,00
85
20
60
60
00
00
85
00
00
50
Mean basin eleva
tion, in
feet
5,760
6,060
5,920
5,820
6,920
5,360
5,699
5,110
5,030
6,180
7,120
6,890
6,390
6,150
5,290
7,390
7,250
6,670
6,300
5,290
6,100
5,120
7,300
6,110
7,670
7,350
6,400
7,950
7,210
6,720
6,360
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
12.0
11.5
10.9
9.8
12.0
8.8
9.0
11.0
10.2
8.8
16.0
15.0
13.4
12.0
9.6
19.8
17.8
16.2
14.8
12.0
12.0
12.0
18.9
16.5
__
25.2
19.1
25.0
22.7
20.2
18.8
45.9
55.9
55.1
55.3
54.7
53.9
54.9
54.2
56.5
60.1
39.7
39.0
54.7
62.5
57.7
55.0
41.0
53.7
54.0
55.0
55.4
55.7
39.5
46.0
39.9
53.2
54.2
44.6
45.6
55.9
50.0
158 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09378950
09379000
09379030
09379060
09379100
09379300
09379560
09379800
09379820
09379980
09381100
09381500
09381800
09382000
09383020
09403000
09403500
09403600
09403700
09403750
09403780
09403800
09404450
09404500
09405420
09405500
09406000
09406300
09406700
09406800
09408000
Relation characteristic L H D 0 U
1
1
1
1
-
-
0
1
-
-
0
0
0
1
1
1
1
0
1
-
1
0
0
1
-
0
0
0
1
0
1
1
1
0
0
-
-
0
0
-
-
0
0
0
0
1
0
0
0
0
-
0
0
0
0
-
0
0
0
1
0
0
0
0
0
0
-
-
0
0
-
-
0
0
0
0
0
0
1
1
1
-
0
0
1
0
-
0
0
0
0
0
0
0
0
0
1
-
-
0
0
-
-
0
0
0
0
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
743728
1,7501,750
8438441820
98
888469463
1,4001,390
264
92864855
2,7702,7402,4802,4803,8803,880
2530
435438701700610622
1,2301,230
90875926127129132142313312
4091,8101,8103,8203,810
141142218219194197361361
5
1,4501,3703,2003,2101,6501,670
4771
255
2,020951922
2,7602,730
698
2522,0601,9804,8604,7205,2905,2306,9906,980
82126
1,0101,0301,3801,3801,3301,4101,7701,860
2611,7602,090
575570293362952925
8843,2603,2507,1807,140
367375531537469494
1,0301,020
10
2,1101,9104,4904,5302,3202,410
80154
406
3,0301,3901,3203,8803,840
1,120
4113,3403,0606,6006,2307,9607,6909,5409,520
161292
1,6001,6401,9201,9401,9902,2002,1402,440
4382,6103,4701,2401,170
453646
1,7101,590
1,2904,4304,41010,1009,990
608626859869739806
1,7501,700
25
3,2102,7806,5906,7103,2903,570
144346
670
4,6902,1101,9705,5405,570
1,850
6905,6704,8209,2308,400
12,40011,50013,30013,300
343673
2,6502,7302,6802,7803,0603,5702,6403,530
7514,0506,0402,7902,400
7291,2103,1802,740
1,9806,1306,09014,50014,2001,0501,0801,4501,4501,1901,3603,0402,840
second) for (years)
50
4,2503,5808,5408,7304,1004,640
213556
922
6,2202,7802,5806,9507,130
2,540
9618,0706,49011,50010,20016,70015,00016,60016,600
5731,1003,6903,7903,2903,5204,0404,8403,0304,590
1,0605,4408,5004,6603,720
9991,7904,7703,870
2,6007,5707,53018,40017,9001,4901,5202,0502,0201,6301,8904,3003,910
100
5,5004,52010,90011,0004,9905,840
306820
1,210
7,8903,5703,2908,4908,880
3,340
1,28011,2008,51014,10012,30021,80018,90020,10020,100
9221,6405,0105,0903,9204,3205,1906,2703,4205,770
1,4307,150
11,3007,3605,4501,3302.4606,8605,250
3,2809,1409,100
22,90022,1002,0502,0502,8202,7002,1402,5005,8505,160
Maximum peak discharge
of record (cubic feet per second)
3,430
8,390
3,100
227
2,060
6,600
2,340
4,590
680
200
7,360
11,600
15,400
16,100
1,610
4,400
2,100
3,030
2,750
150
4,630
1,950
640
3,210
1,740
9,150
22,800
1,000
1,910
938
2,980
Basin, Climatic, and Flood Characteristics 159
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09408150
09408200
09408400
09409500
09410000
10242000
10242100
10242440
09093500
09095000
09128500
09130500
09132500
09134500
09137800
09141200
09238500
09239500
09241000
09244100
09245000
09245500
09248600
09249000
09249200
09250000
09253000
09255000
09255500
09256000
09257000
Flood Station name region
Virgin River near Hurricane, Utah
Fort Pierce Wash near St. George,UtahSanta Clara River near Pine Valley,Utah
Moody Wash near Veyo, Utah
Santa Clara River above WindsorDam near Santa Clara, Utah
Coal Creek near Cedar City, Utah
Shirts Creek near Cedar City,Utah
Cottonwood Creek near Enterprise,Utah
Parachute Creek at Grand Valley,Colo.
Roan Creek near De Beque, Colo.
Smith Fork near Crawford, Colo.
East Muddy Creek near Bardine,Colo.North Fork Gunnison Rivernear Somerset, Colo.Leroux Creek near Cedaredge,Colo.Dirty George Creek near GrandMesa, Colo.
Youngs Creek near Grand Mesa,Colo.
Walton Creek near Steamboat Springs,Colo.
Yampa River at Steamboat Springs,Colo.
Eli River at Clark, Colo.
Fish Creek near Milner, Colo.
Elihead Creek near Elihead, Colo.
North Fork Elihead Creek nearElihead, Colo.
East Fork of Williams Fork aboveWillow Creek, Colo.
East Fork of Williams Fork nearPagoda, Colo.
South Fork of Williams Fork nearPagoda, Colo.
Milk Creek near Thornburg, Colo.
Little Snake River near Slater, Colo.
Slater Fork near Slater, Colo.
Savery Creek at Upper Station,near Savery, Wyo.Savery Creek near Savery, Wyo.
Little Snake River near Dixon,
8
8
8
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
Lati
tude, in decimal degrees
37.
37.
37.
37.
37.
37.
37.
37.
39.
39,
38.
39.
38.
38,
38.
38.
40.
40.
40.
40.
40.
40.
40.
40.
40.
40.
40.
.162
.060
,383
,433
,218
.672
.617
.567
.453
,453
.728
.013
.929
,927
.945
.958
.408
.484
.717
.334
.670
.681
.261
.312
,212
.194
.999
40.982
41.
41.
41.
.218
,098
.028
Longi
tude, in decimal degrees
113.395
113.544
113.482
113.742
113.776
113.034
113.117
113.700
108.059
108.316
107.506
107.358
107.448
107.793
108.027
107.918
106.786
106.832
106.915
107.139
107.285
107.287
107.294
107.319
107.442
107.732
107.143
107.383
107.372
107.381
107.549
System
atic Drainage years area, in of square
record miles
20
11
27
15
30
56
16
11
21
23
50
19
52
29
12
12
19
79
58
18
34
15
16
18
13
34
40
55
23
32
52
1,499.
1,650.
18.
33.
338.
80.
12.
6.
198.
321.
42,
133.
526.
34.
10.
10.
42.
604.
216.
34.
64.
21.
108.
150.
46.
65.
285.
161.
200.
330.
988.
00
00
70
00
00
,90
.80
,00
,00
,00
,80
,00
.00
,50
,60
,30
,40
,00
,00
,50
,20
,00
,00
.00
.70
00
,00
,00
00
00
00
Mean basin eleva
tion, in
feet
6,350
4,870
8,720
6,070
5,900
8,640
8,032
6,110
7,500
7,500
9,200
8,700
8,900
9,700
9,700
9,300
9,300
8,800
9,000
8,200
8,400
8,600
9,600
9,200
9,200
7,800
8,600
8,400
7,790
7,870
8,030
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
18.7
9.0
27.3
13.7
15.6
28.8
25.3
11.0
16.0
18.0
23.0
26.0
25.0
33.0
24.0
25.0
49.0
25.0
37.0
23.0
26.0
41.0
29.0
26.0
32.0
18.0
31.0
22.0
21.0
19.0
18.0
57.3
59.4
43.8
45.2
55.2
43.7
45.3
57.4
40.8
40.0
40.1
40.8
40.2
40.0
39.3
39.9
38.9
40.8
39.1
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
41.1
41.9
41.7
41.8Wyo.
160 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09408150
09408200
09408400
09409500
09410000
10242000
10242100
10242440
09093500
09095000
09128500
09130500
09132500
09134500
09137800
09141200
09238500
09239500
09241000
09244100
09245000
09245500
09248600
09249000
09249200
09250000
09253000
09255000
09255500
09256000
09257000
Relation
L
1
1
0
1
0
1
0
1
0
0
1
0
1
1
0
0
0
0
1
0
1
0
0
0
1
1
0
1
0
1
1
H
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
D
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
u
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
5,9405,9002,3402,420
7578
267274940951785784269269145148429430567568375375914913
3,5903,590
69769644475557
1,3801,3703,7003,7002,6702,670
159160
1,0201,020
402401
1,0101,010
923924628627355355
2,2502,250
857857459460
1,2001,2004,6804,670
5
10,40010,2004,5005,060
163184868900
2,3802,4401,6601,650
495501398418886888
1,1101,110
578581
1,3101,3105,0605,020
92291968917291
1,8301,7904,6504,6303,3603,340
245255
1,4601,440652642
1,2901,3001,2401,250
766769623622
3,0503,0301,2101,210
837844
1,6601,6506,1606,110
10
13,90013,3006,3607,840
250312
1,5601,6103,8503,9702,4902,450
684709684729
1,2901,2901,5301,540
734742
1,5901,5806,0605,9701,0701,070
8414281
1332,1102,0205,1905,1503,7803,730
303336
1,7701,730
838813
1,4601,4801,4501,480
850869842841
3,5503,4901,4601,4601,1401,1601,9401,9407,0706,950
feet per interval
25
19,10017,7009,24012,700
406566
2,8302,8606,4006,6103,8703,750
9691,0601,2401,3101,9201,9202,1202,160
956969
1,9701,9607,3507,1601,2501,240
10421092
1932,4602,3005,8005,7404,2604,180
373452
2,1802,1101,1001,0501,6501,6901,7101,770
9501,0001,1701,1704,1404,0501,7801,7901,6001,6502,2902,3208,1707,980
second) for (years)
50
23,50021,50011,80017,200
561826
4,1104,0408,8509,0905,1704,9401,2201,3901,8201,8902,4902,5102,5902,6801,1401,1502,2702,2608,3208,0701,3801,360
11824999
2322,7102,5006,2106,1404,5904,490
424549
2,4902,4101,3001,2401,7901,8301,9101,9801,0201,1001,4401,4604,5504,4402,0202,0401,9802,0702,5302,6108,9608,750
100
28,40025,60014,70022,000
7581,1405,7005,410
11,80012,0006,7306,3401,4901,7602,6002,5903,1303,1203,0903,1901,3401,3602,5902,5909,3008,9801,5201,510
132305106283
2,9602,7206,5806,5104,9004,790
473641
2,8102,7101,5201,4401,9302,0102,1002,2101,0901,2101,7501,7604,9604,8402,2702,3102,4002,5002,7702,8909,7109,470
Maximum peak discharge
of record (cubic feet per second)
20,100
8,760
776
1,810
6,190
4,620
1,070
1,470
2,600
2,020
1,410
2,190
9,220
1,310
86
86
2,800
6,820
4,910
342
2,850
1,100
1,570
1,620
910
1,580
4,780
2,250
1,680
2,670
13,000
Basin, Climatic, and Flood Characteristics 161
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09257500
09258000
09258200
09258900
09259500
09263700
09263800
09271800
09302800
09303000
09303500
09304000
09304200
09304300
09304500
09304800
09306007
09306061
09306200
09306222
09306235
09306242
09306255
09306800
09307500
09308000
09308200
09308500
09309000
09309100
09404310
Station name
Willow Creek near Baggs, Wyo.
Willow Creek near Dixon, Wyo.
Dry Cow Creek near Baggs, Wyo.
Muddy Creek above Baggs , Wyo .
Fourmile Creek near Baggs, Wyo.
Cliff Creek near Jensen, Utah
Cow Wash near Jensen, Utah
Halfway Hollow Tributarynear Lapoint, UtahNorth Fork White River nearBuford, Colo.
North Fork White River atBuford, Colo.South Fork White River nearBuford, Colo.
South Fork White River at Buford,Colo.
White River above Coal Creek,near Meeker, Colo.Coal Creek near Meeker, Colo.
White River near Meeker, Colo.
White River below Meeker, Colo.
Piceance Creek below Rio Blanco,Colo.Piceance Creek above Hunter Creeknear Rio Blanco, Colo.Piceance Creek below Ryan Gulchnear Rio Blanco, Colo.Piceance Creek at White River,Colo.
Coal Gulch below Water Gulchnear Rangely, Colo.Coal Gulch near Rangely, Colo.
Yellow Creek near White River,Colo.
Bitter Creek near Bonanza, Utah
Willow Creek above diversions.near Ouray, UtahWillow Creek near Ouray, Utah
Pleasant Valley WashTributary near My ton, Utah
Minnie Maud Creek near My ton,Utah
Minnie Maud Creek at Nutter Ranchnear My ton, UtahGate Canyon near Myton, Utah
Yampai Canyon Tributary, near
Flood region
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
10
Lati
tude, in decimal degrees
40
40
41
41
40
40
40
40
40
39
39
39
40
40
40
40
39
39.
39.
40.
39.
39.
40.
39.
39.
39.
40.
39.
39.
39.
35.
.877
.916
.340
.132
.841
.300
.317
.417
.036
.987
.922
.974
.005
.091
.034
.013
.826
.851
.921
.088
.906
.920
.169
.753
,566
,939
,117
799
812
833
552
Longi
tude, in decimal degrees
107
107
107
107
107
109
109
109
107
107
107
107
107
107
107
108
108
108
108
108
108
108
108
109
109
109
110
110
110
110
113
.464
.521
.671
.646
.514
.133
.217
.750
.520
.614
.551
.625
.825
.769
.862
.092
.182
.258
.297
.243
.532
.472
.401
.354
.587
.648
.133
.565
.250
.250
.388
System
atic Drainage years area, in of square
record miles
10
32
12
14
11
15
14
15
17
35
27
35
25
11
78
24
13
13
22
18
11
13
11
16
27
26
11
32
23
12
13
5.00
24.00
49.70
1,178.00
4.00
64.00
3.90
5.60
220.00
260.00
152.00
177.00
648.00
25.10
755.00
1,024.00
177.00
309.00
506.00
652.00
8.61
31.60
262.00
324.00
297.00
897.00
15.00
32.00
231.00
5.40
0.20
Mean basin eleva
tion, in
feet
9,000
8,200
6,950
7,000
8,600
6,570
5,360
6,547
9,734
9,529
10,060
9,800
9,142
7,956
8,940
8,449
7,628
7,552
7,415
7,269
7,740
7,490
6,877
7,146
7,650
7,080
6,110
8,460
7,880
6,860
5,360
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
20.0
19.0
11.0
12.0
20.0
14.0
10.5
10.8
31.5
30.9
33.6
36.3
30.7
28.4
29.6
27.5
24.5
21.2
20.8
20.0
20.0
20.0
17.3
16.1
16.8
13.7
10.3
18.7
16.8
13.6
12.2
40.7
41.1
44.1
42.7
40.7
44.6
45.0
38.5
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
40.0
39.9
39.4
45.2
41.1
37.8
39.4
39.5
71.6Peach Springs, Ariz.
162 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Statas
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09257SOO
09258000
09258200
09258900
09259500
09263700
09263800
09271800
09302800
09303000
09303500
09304000
09304200
09304300
09304500
09304800
09306007
09306061
09306200
09306222
09306235
09306242
09306255
09306800
09307500
09308000
09308200
09308500
09309000
09309100
09404310
Relation characteristic L H D 0 U
1
1
-
0
0
1.
1
1
1
1
1
1
1
0
1
1
1
0
0
0
0
0
-
0
1
1
-
0
1
1
-
0
0
-
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
-
0
1
1
-
0
0
0
-
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
-
0
0
0
-
1
0
-
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
1
1
0
0
-
0
0
0
-
0
0
0
-
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
0
0
0
1
Peak discharge (cubic indicated recurrence
2
8990
161161
1936476548181
1831833113089393
1,3301,3301,3901,3901,8701,8701,9401,9403,3003,300
4951
3,2703,2703,4003,390
20120520020614114623824415166465
508125130242245663666
-__-
59107108538539282279
5
5
102112260264
3741,3301,360
131135754735770732288279
1,6101,6301,8601,8702,3802,3702,3802,3704,2904,260
80100
4,2604,2504,5404,500
35939240344926830942947797
104312315
854546570470491
1,7401,740
139365369818830625594
33
10
109140329341
5651,9202,000
167180
1,5001,4101,2701,140
510475
1,7801,8402,1702,1902,7102,6802,6502,6304,9004,820
102161
4,9004,8805,2805,180
485578576701381499578717256262717696
1,2401,1601,190
689747
2,9802,950
237676677
1,0301,070928836
74
feet per second) for interval (years)
25
117186419450
9442,8003,030
214246
2,9902,6802,2101,880
926830
1,9802,0902,5702,5903,1103,0402,9702,9305,6405,500
131267
5,7105,6706,1806,030
668885835
1,120561835789
1,130717667
1,7501,590
2,0202,5402,5101,0701,2005,4005,230
4691,2801,2501,3201,4201,3901,190
141
50
122220486538
1,4303,5604,020
250300
4,5904,0403,2002,6701,3501,2002,1202,2302,8702,8803,4103,3003,2003,1406,1805,990
153364
6,3006,2406,8406,680
8201,1701,0601,510
7261,170
9611,5301,3901,2203,1002,700
3,0204,2004,0501,4401,6308,0207,700
8371,9101,8401,5601,7301,8001,520
201
100
127260554625
1,6504,4004,920
286353
6,6405,6404,4903,6201,8901,6302,2502,4303,1803,2103,7003,5803,4303,3806,7006,490
176452
6,8906,8307,4907,330
9861,4301,3001,860
9191,4801,1401,8702,5302,0605,2104,310
3,4606,5406,0001,9002,12011,60010,900
9722,7202,5701,8102,0202,2501,850
280
Maximum peak discharge
of record (cubic feet per second)
115
476
853
2,650
168
1,360
2,950
702
1,950
3,550
3,620
3,150
5,740
102
6,950
6,590
520
612
550
625
272
1,780
6,800
1,790
2,240
11,000
2,590
1,370
1,380
1,000
177
Basin, Climatic, and Flood Characteristics 163
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09404350
09415050
09415100
09417100
09418990
09419590
09419620
09419630
09419640
09419647
09419650
09419663
09419670
09419675
09419677
09419680
09419690
09419697
09421800
09423300
09423400
09423760
09423820
09423900
09424050
09427700
09428530
09428560
09428570
09429150
09429240
Station name
Valentine Wash at Valentine, Ariz.
Big Bend Wash Tributarynear Littlefield, Ariz.Pulsipher Wash near Mesquite, Nev.
Dry Lake Tributary near NeLLisAir Force Base, Nev.
Weiser Wash near Glendale, Nev.
Detrital Wash Tributary nearChloride, Ariz.
Mormon Wells Wash near Las Vegas,Nev.
Telephone Canyon near CharlestonPark, Nev.
Kyle Canyon near Charleston Park,Nev.
Las Vegas Wash Tributary nearLas Vegas, Nev.
Las Vegas Wash at North Las Vegas,Nev.
Las Vegas Wash Tributary south ofNellis Air Force Base, Nev.
Red Rock Wash near Blue Diamond,Nev.
Flamingo Wash at Las Vegas, Nev.
Flamingo Wash at Maryland Parkwayat Las Vegas, Nev.
Cottonwood Valley near BlueDiamond, Nev.
Duck Creek at Whitney, Nev.
Las Vegas Wash Tributarynear Henderson, Nev.Ringbolt Wash near Hoover Dam,Ariz.Piute Wash Tributary at Searchlight,Nev.
Tin Can Creek near Needles, Calif.
Little Meadow Creek near Oatman,Ariz.Sacramento Wash near Yucca, Ariz.
Sacramento Wash Tributary nearTopock, Ariz.
Chemehuevi Wash Tributary nearNeedles, Calif.
Monkeys Head Wash near Parker,Ariz.
Arch Creek near Earp, Calif.
Colorado River Tributary No 2near Vidal, Calif.
Colorado River Tributary nearVidal, Calif.Creosote Wash near Ehrenberg, Ariz.
Ogilby Wash near Palo Verde, Calif.
Flood region
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Lati
tude, in decimal degrees
35
36
36
36
36
35
36
36
36
36
36
36
36
36
36
36
36
36
35
35
34
35
34
34
34
34
34
33
33
33
33
.383
.862
.801
.354
.668
.432
.446
.272
.278
.303
.211
.194
.158
.116
.143
.010
.086
.031
.968
.467
.857
.030
.811
.730
.508
.278
.165
.986
.980
.621
.339
System-
Longi- atic Drainage tude.in years area, in decimal of square degrees record miles
113.662
113.968
114.110
114.909
114.536
114.285
115.253
115.542
115.469
115.139
115.106
115.025
115.496
115.184
115.070
115.431
115.033
115.030
114.683
114.939
114.882
114.308
114.161
114.312
114.603
114.129
114.372
114.496
114.506
114.495
114.779
14
13
18
12
16
15
25
25
26
24
21
23
25
18
18
26
26
18
14
17
15
12
12
14
14
14
14
14
14
12
14
3.
7.
4,
10,
43.
1.
115,
7,
35
62
700
1
8.
86
106
18
239
1
1
3
0
8
787
14
2
1
1
0
1
1
0
,15
,27
.58
.00
,00
.23
.00
.20
.90
.00
.00
.20
.09
.00
.00
.30
.00
.17
.21
.40
.04
.47
.00
.70
.04
.84
.52
.42
.12
.98
.04
Mean basin eleva
tion, in
feet
4,490
2,240
1,950
2,690
2,480
3,710
6,500
7,880
8,020
3,790
--
2,510
6,030
3,790
3,200
5,400
3,420
2,370
2,590
3,670
2,600
3,400
3,400
1,450
1,130
840
880
--
509
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
12.1
7.6
6.0
6.0
6.0
10.1
6.0
10.0
10.1
6.0
6.0
4.0
7.0
6.0
6.0
8.3
6.0
6.0
5.8
6.0
6.0
12.0
10.1
6.2
7.0
5.5
6.0
5.0
5.0
5.5
59.6
59.6
62.3
64.5
64.3
64.4
54.5
65.2
65.3
60.2
64.3
67.8
67.0
76.0
75.6
70.1
75.9
79.1
80.8
74.7
76.0
71.8
73.0
74.2
88.4
74.9
79.3
74.7
74.5
89.0
100.0
164 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09404350
09415050
09415100
09417100
09418990
09419590
09419620
09419630
09419640
09419647
09419650
09419663
09419670
09419675
09419677
09419680
09419690
09419697
09421800
09423300
09423400
09423760
09423820
09423900
09424050
09427700
09428530
09428560
09428570
09429150
09429240
Relation characteristic L H D 0 U
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
00000
- - - - 1
- - - - 1
10100
01000
- - - - 1
- - - - 1
10100
00000
- - - - 1
11000
- - - - 1
- - - - 1
10000
- - - - 1
- - _ - !
- - - - 1
- - - - 1
- - - - 1
00000
00000
- - - - 1
- - - - 1
00000
00000
Peak discharge (cubic indicated recurrence
2
....
23
38
29____
46
106
141216
____
38____
964648
254262
13
40199198264261
65337336
13
136968
2
41
574
57
1818182525
7
13969265
5
....
167
274
209
331
782
9671
218
272
703304381
1,2001,570
95
292714783
1,2101,230
472698854
93
95173173
13
300
4,350
415
129100104193178
51
912402171515
10
....
407
684
514
834
2,060
227171610
680
1,840825
1,0502,7303,980
224
7311,3701,6602,6502,800
1,2101,0601,640
220
225275301
27
752
12,500
1,060
311236247526473
117
2153883702626
feet per interval
25
....
843
1,450
1,080
1,790
4,610
458432
1,190
1,440
4,1002,4102,7306,5808,880
450
1,5602,7203,2706,0906,360
2,6501,7002,780
443
453445501
49
1,600
30,500
2,300
636572575
1,4601,320
228
4316516464546
second) for (years)
50
....
1,270
2,230
1,640
2,760
7,330
678773
2,300
2,210
6,5004,8505,39011,70016,500
667
2,3904,2205,35010,40010,900
4,1402,3504,640
655
670605722
68
2,470
51,400
3,570
9511,000
9792,7502,380
330
6379109156465
100
....
1,880
3,340
2,430
4,160
11,400
9811,3003,030
3,320
10,1009,1209,59019,50025,100
964
3,6006,2307,560
16,80017,300
6,3203,1705,850
947
969793930
92
3,710
84,700
5,430
1,3901,6401,5904,7804,280
467
9191,2301,250
8889
Maximum peak discharge
of record (cubic feet per second)
3,800
250
1,880
180
584
470
480
2,500
1,660
5,130
12,010
296
7,470
3,910
4,700
1,100
3,570
1,950
310
400
98
869
13,000
1,030
114
320
7,160
400
460
580
39
Basin, Climatic, and Flood Characteristics 165
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09429250
09429400
09429510
10248490
10248510
10250600
10250720
10251000
10251200
10251220
10251270
10251271
10251272
10251350
10251400
10251500
10251600
10251980
10252300
10252550
10253000
10253250
10253255
10253350
10253700
10253750
10253800
10254020
10254475
10255200
10255230
Flood Station name region
Ogilby Wash No. 2 near Palo Verde,Calif.Indian Wash Tributary near Yuma,Ariz.
Mittry Lake Tributary near Yuma,Ariz.Indian Springs Valley Tributarynear Indian Spring, Nev.Eldorado Valley Tributary nearNelson, Nev.
Wildrose Creek near Wildrose Station,Nev.
Onyx Creek near Ballarat,Nev.
Big Dip Creek near Stovepipe Wells,Nev.
Spring Cceek at Furnace Creek Inn,Nev.
Amargosa River near Beatty, Nev.
Amargosa River Tributary nearMercury, Nev.Amargosa River Tributary No. 1 nearJohnnie, Nev.
Amargosa River Tributary No. 2 nearJohnnie, Nev.
Horse Thief Creek near Tecopa,Nev.Ibex Creek near Tecopa, Nev
Yucca Creek near Yucca Grove,Calif.
Sal. sherry Creek near Sho shone,Calif.Lovell Wash near Blue Diamond,Nev.
China Spring Creek near MountainPass, Calif.
Caruthers Creek near Ivanpah, Nev.
Gourd Creek near Ludlow, Calif.
Granite Wash near Rice, Calif.
Granite Wash No. 2 near Rice,Calif.
Fortynine Palms Creek nearTwentynine Palms, Calif.
Palen Dry Lake Tributary nearDesert Center, Calif.
Monument Wash near Desert Center,Calif.
Coxcomb Wash near Desert Center,Calif.
Betz Wash near Salton Beach,Calif.
Glamis Wash at Glamis, Calif.
Myer Creek Tributary nearJacumba, Calif.
Myer Creek Tributary No. 2 near
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Lati
tude , in decimal degrees
33
33
32
36
35
36
36
36
36
36
36
36
36
35
35
35
35
36
35
35
34
34
34
34
33
33
33
33
32
32
32
.340
.109
.860
.567
.810
.265
.022
.918
.444
.868
.561
.460
.436
.781
.787
.408
.919
.003
.468
.242
.676
.047
.049
.120
.696
.708
.807
.498
.998
.674
.721
Longi
tude, in decimal degrees
114
114
114
115
114
117
117
117
116
116
116
116
116
115
116
115
116
115
115
115
116
115
115
116
115
115
115
115
115
116
116
.779
.295
.435
.811
.885
.178
.312
.293
.837
.759
.100
.108
.074
.897
.333
.772
.435
.644
.508
.299
.022
.218
.217
.095
.479
.364
.286
.904
.069
.081
.046
System
atic Drainage years area, in of square
record miles
14
15
12
22
18
15
11
15
15
19
22
18
17
10
15
15
15
17
15
23
22
14
14
18
14
14
14
14
15
14
14
0.01
2.56
0.30
29.00
1.41
23.70
0.52
0.95
0.21
70.00
110.00
2.21
2.49
3.06
0.20
0.03
0.01
52.80
0.94
1.13
0.30
0.01
0.01
8.55
0.04
4.29
0.03
5.95
0.60
0.11
0.08
Mean basin eleva
tion, in
feet
_
1,190
346
6,140
2,900
6,400
--
2,200
--
5,070
4,060
3,460
4,640
--
2,150
6,390
--
6,200
1,800
__
4,200
--
400
2,000
1,160
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
__
5.5
4.2
6.6
6.0
8.0
5.0
5.0
2.0
7.1
6.0
6.0
6.8
5.0
3.0
9.0
7.0
10.0
3.0
__
5.0
4.0
--
3.0
3.0
4.0
4.0
100.0
68.7
73.6
66.0
80.1
75.0
75.0
62.7
75.1
59.5
75.2
75.4
75.0
75.8
80.2
75.0
80.1
64.8
74.9
75.0
80.0
100.0
100.0
79.7
90.8
93.8
92.6
73.6
80.0
61.8
68.6Coyote Wells, Calif.
166 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09429250
09429400
09429510
10248490
10248510
10250600
10250720
10251000
10251200
10251220
10251270
10251271
10251272
10251350
10251400
10251500
10251600
10251980
10252300
10252550
10253000
10253250
10253255
10253350
10253700
10253750
10253800
10254020
10254475
10255200
10255230
Relation characteristic L H D 0 U
10000
00000
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
01000
00000
- - - - 1
10100
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
00100
- - - - 1
- - - - 1
- - - - 1
- - - - 1
- - - - 1
10000
- - - - 1
- - - - 1
- - - - 1
00000
- - - - 1
Peak discharge (cubic indicated recurrence
2
11114544
6
85
15
75
8131344
4263539
19
20
23
5
2
1
120
123535
6
1
1
42
21819
2
34
911
5
20176579
42
620
104
550
5838451216
3,210272408
136
146
164
33
11
6
883
82235218
42
6
6
301
135380
11
243
638
11
10
262379131
95
1,610
247
1,420
13366902031
9,070805
1,200
327
352
400
74
23
12
2,340
192605554
95
12
12
757
2789
169
23
604
1462732
feet per interval
25
363398189
183
3,570
500
3,130
2611221603450
21,8002,5903,190
670
724
828___-
141
41
20
5,270
3841,6101,500
183
20
20
1,610
49153286
41
1,280
2879796
second) for (years)
50
4340113289
263
5,630
743
4,920
3811842524876
36,4005,5406,590
1,000
1,090
1,250
201
56
27
8,410
5662,9602,680
263
27
27
2,490
68214467
56
1,950
419216201
100
5149129322
370
8,680
1,080
7,550
5412673386493
59,30011,00012,000
1,470
1,600
1,840
280
76
35
13,100
8145,0904,720
370
35
35
3,740
92287565
76
2,910
598441406
Maximum peak discharge
of record (cubic feet per second)
32
98
165
497
530
1,060
24
199
24
16,000
3,430
350
125
850
126
24
12
4,150
113
671
125
22
27
1,240
52
100
75
133
86
41
2119 42 77 109 149
Basin, Climatic, and Flood Characteristics 167
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10255650
10255700
10255730
10255800
10255820
10255825
10255850
10255885
10256000
10256400
10256500
10257600
10258000
10258100
10258500
10259000
10259200
10259300
10259500
10259600
10260200
10260400
10261000
10261500
10261800
10262600
10263100
10263500
10263900
10264000
10264520
Station name
Chariot Creek near Julian, Calif.
San Felipe Creek near Julian,Calif.Pinyon Wash near Borrego SpringsCalif.
Coyote Creek near BorregoSprings, Calif.
Yaqui Pass Wash near Borrego,Calif.
Yaqui Pass Wash No. 2 nearBorrego, Calif.
Vallecito Creek near Julian,Calif.San Felipe Creek near Westmorland,Calif.Whitewater River at Whitewater,Calif.San Gornonio River near Whitewater,Calif.Snow Creek near Whitewater,Calif.
Mission Creek near Desert HotSprings, Calif.
Tahquitz Creek near Palm Springs,Calif.Palm Canyon Creek Tributary nearAnza, Calif.Palm Canyon Creek near Palm Springs,Calif.
Andreas Creek near Palm Springs,Calif.
Deep Creek near Palm Desert, Calif.
Whitewater River at Indio, Calif.
Thermal Canyon Tributary nearMecca, Calif.Cottonwood Wash near CottonwoodSpring, Calif.
Pipes Creek near Yucca Valley,Calif.Cushenbury Creek near LucerneValley, Calif.
West Fork Mohave River nearHesperia, Calif.
Mohave River at Lower Narrows ,near Victorville, Calif.Beacon Creek at Helendale, Calif.
Boom Creek near Barstow, Calif.
ZZYZX Creek near Baker, Calif
Big Rock Creek near Valyermo,Calif.Buckhorn Creek near Valyermo,Calif.
Little Rock Creek near LittleRock, Calif.Amargosa Creek Tributary nearPalmdale, Calif.
Flood region
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Lati
tude, in decimal degrees
33
33
33
33
33
33
32
33
33
33
33
34
33
33
33
33
33
33
33
33
34
34
34
34
34
34
35
34
34
34
34
.066
.119
.115
.374
.147
.151
.986
.124
.947
.921
.871
.011
.805
.569
.745
.760
.631
.735
.680
.744
.172
.364
.341
.573
.750
.906
.194
.421
.343
.463
.631
Longi
tude, in decimal degrees
116.552
116.434
116.317
116.427
116.350
116.349
116.419
115.852
116.640
116.696
116.680
116.627
116.558
116.512
116.535
116.549
116.391
116.244
115.990
115.826
116.546
116.845
117.240
117.320
117.315
116.949
116.151
117.839
117.920
118.018
118.326
System
atic Drainage years area, in of square
record miles
12
25
14
36
14
14
20
26
30
14
26
18
38
12
52
37
24
20
14
14
21
20
49
39
17
23
11
64
20
47
15
7.
89.
19.
144.
0.
0.
39.
1693.
57.
154.
10.
35.
16.
0.
93.
8.
30.
1,073.
0.
0.
15.
6.
70.
513.
0.
0.
0.
22.
0.
49.
0.
95
20
60
00
03
04
,70
00
50
,00
,80
60
.90
.47
,10
,65
,60
,00
,18
71
,10
,36
,30
,00
,72
24
,23
,90
,48
,00
,05
Mean basin eleva
tion, in
feet
4,000
3,400
2,750
4,300
--
5,600
--
6,150
--
6,800
5,200
4,500
4,500
4,000
1,700
--
4,120
4,500
2,700
2,350
1,800
6,000
7,600
5,600
3,440
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
27.0
10.0
7.0
6.0
--
--
--
26.0
--
29.0
--
24.0
12.0
10.0
14.0
8.0
4.0
5.0
9.0
12.0
24.0
5.0
4.0
5.0
3.0
18.0
25.0
21.0
9.0
60.9
59.8
59.7
59.9
60.0
60.0
70.3
65.4
60.6
51.3
58.2
61.1
61.4
70.8
65.2
63.9
70.0
70.0
80.5
80.8
79.8
69.6
69.3
80.3
80.3
75.2
80.7
81.0
79.5
84.0
84.6
168 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10255650
10255700
10255730
10255800
10255820
10255825
10255850
10255885
10256000
10256400
10256500
10257600
10258000
10258100
10258500
10259000
10259200
10259300
10259500
10259600
10260200
10260400
10261000
10261500
10261800
10262600
10263100
10263500
10263900
10264000
10264520
Relation characteristic L H D 0 U
0
0
-
0
0
0
1
0
1
0
0
0
0
1
1
1
1
0
-
-
-
-
0
1
1
1
-
0
0
1
1
0
1
-
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
-
-
-
-
0
0
0
0
-
0
0
0
0
0
0
-
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
-
-
-
-
1
1
0
0
-
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
-
-
-
0
0
0
0
-
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
0
0
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
12141721
67308306
2222
4849
2,8702,820
4654583963893573504042919156
3753737675
352345478484
4
10
58
351,9201,9001,3101,300
13132424
51831821818
520515
55
5
77121123243
4921,3501,370
11111010
241309
8,7908,5801,9301,8401,7901,7701,2701,170
3774254294311422
1,3601,350
251255
1,3201,2404,4004,510
31
69
422
2536,8606,5107,6107,300
44484947
367407316463
1,8901,830
910
10
201318370718
1,2702,7402,880
27272122
533743
16,40016,8004,4604,2503,8804,0102,5902,3901,2101,310
9839972245
2,6502,690
490513
2,6102,49013,10013,400
69
162
1,080
63013,40012,70018,90018,100
85987072
801,5301,520
123124
3,6403,540
1316
25
569736
1,2801,840
2,7705,5605,860
63644546
1,1901,540
32,70034,20011,70011,2008,7609,0305,7205,3804,1604,1502,4202,430
3772
5,3505,4501,0301,0705,4005,240
39,80039,500
131
320
2,340
1,33027,60026,60049,30047,700
176195103108
1543,3403,330
244244
7,2107,100
1824
second) for (years)
50
1,1201,3802,9603,990
4,3308,5909,240
1211097372
1,9602,65052,00055,70022,70021,40014,70015,2009,7208,9709,2008,7804,3704,340
50115
8,4008,6301,7001,7608,6008,270
79,50077,300
187
469
3,640
2,04044,10042,00091,40087,400
286316132144
2205,5205,490
380377
11,10010,900
2333
100
2,0702,3006,4607,470
6,62012,50013,300
199182111108
3,0303,800
79,70084,70042,50040,50023,40024,00015,90015,00018,80017,8007,4707,390
66134
12,60012,9002,7002,76013,10012,800
145,000141,000
260
671
5,530
3,05067,30065,100
159,000154,000
447474165178
3088,6708,630
564559
16,30016,100
2939
Maximum peak discharge
of record (cubic feet per second)
340
6,150
19,200
3,890
38
25
1,160
100,000
42,000
7,250
13,000
1,750
2,900
28
7,000
1,960
7,100
14,100
128
34
640
530
26,100
70,600
360
125
46
8,300
169
17,000
19
Basin, Climatic, and Flood Characteriatics 169
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
10261,530
10261,560
10261,605
10264680
10264700
10264750
10264840
10264878
10264900
10264915
09383500
09384000
09384200
09385800
09386100
09387050
09390500
09392800
09393500
09395100
09395400
09395500
09395600
09395900
09396400
09397200
09397500
09397800
09398000
09398500
09399000
Station name
Pine Creek near Palmdale, Calif.
Spencer Canyon Creek near Fairmont,Calif.Joshua Creek near Mohave,Calif.
Mescal Creek Tributary atBig Pines, Calif.Peewee Creek near Randsburg, Calif.
Pine Tree Creek near Mohave,Calif.Sand Creek near Inyokern, Calif.
Ninemile Creek near Brown,Calif.Salt Wells Creek near Westend,Calif.
Crust Creek near Westend,Calf.
Nutrioso Creek above NelsonReservoir near Springerville, Ariz.Little Colorado River aboveLyman Lake near St. Johns, Ariz.
Lyman Reservation Tributary nearSt. Johns, Ariz.
Little Colorado River Tributarynear St. Johns, Ariz.Largo Creek near Quemado, N. Hex.
Galestena Canyon Tributarynear Black Rock, N. Hex.Show Low Creek near Lakeside,Ariz.Long Lake Tributary near Show Low,Ariz.Silver Creek near Snowflake, Ariz.
Carr Lake Tributary near Holbrook,Ariz.
Milk Rock Canyon near Ft Wingate,N. Hex.Puerco River at Gallup, N. Mex.
Wagon Trail Wash near Gamerco,N. Mex.
Black Creek near Lupton, Ariz.
Dead Wash Tributary near Holbrook,Ariz.Penzance Wash near Joseph City,Ariz.Chevelon Creek below Wildcat Canyon,near Winslow, Ariz.
Brookbank Canyon near Heber, Ariz.
Chevelon Creek near Winslow, Ariz.
Clear Creek below Willow Creek,near Winslow, Ariz.
Clear Creek near Winslow, Ariz.
Flood region
10
10
10
10
10
10
10
10
10
10
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
Lati
tude , in decimal degrees
34.
34.
35.
34.
35.
35.
35.
35.
35.
35.
34.
34.
34.
34.
34.
34.
34.
34.
34.
34.
35.
35.
35.
35.
35.
34.
34.
34.
34.
34.
34.
602
776
012
374
461
231
624
843
656
690
032
314
392
451
324
979
179
261
667
835
432
529
650
452
075
919
636
472
926
667
969
Longi
tude, in decimal degrees
118.247
118.569
118.344
117.700
117.656
118.085
117.890
117.926
117.447
117.381
109.186
109.362
109.380
109.256
108.528
108.667
109.987
109.995
110.042
109.933
108.558
108.745
108.783
109.126
109.750
110.254
110.714
110.647
110.531
111.007
110.644
System
atic Drainage years area, in of square
record miles
24
21
15
12
15
20
15
15
15
14
17
46
14
14
32
30
33
12
56
13
35
34
24
19
13
14
28
13
48
39
52
1
3
3
0
0
33
1
10
61
0
83
747
0
0
151
19
68
5
886
1
14.
558,
0,
500,
1.
0.
275.
27.
794.
321.
607.
.37
.60
.83
.05
.14
.50
.02
.40
.60
.13
.40
.00
.24
.35
.00
.00
.60
.18
.00
.19
.00
.00
.38
,00
,00
,17
.00
.60
.00
00
00
Mean basin eleva
tion, in
feet
3,300
4,300
7,400
3,400
5,000
--
1,700
8,550
7,760
6,100
6,350
8,270
7,100
7,320
6,700
6,400
5,420
8,300
7,900
6,500
7,500
5,740
5,150
7,030
6,950
6,440
7,100
6,500
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
13.0
10.0
12.0
9.0
6.0
7.0
--
5.0
20.0
20.0
11.6
11.1
15.6
12.8
23.7
13.5
16.7
7.8
15.5
12.9
11.5
15.8
7.9
7.8
24.0
22.1
18.4
25.8
18.7
85.2
59.3
54.7
77.6
80.5
71.2
75.0
71.8
75.0
75.0
44.4
51.8
52.1
52.3
48.7
50.4
49.0
51.3
55.7
55.3
49.7
50.0
50.0
49.9
54.0
55.0
54.3
52.3
55.6
52.3
55.6
170 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
10264530
10264560
10264605
10264680
10264700
10264750
10264840
10264878
10264900
10264915
09383500
09384000
09384200
09385800
09386100
09387050
09390500
09392800
09393500
09395100
09395400
09395500
09395600
09395900
09396400
09397200
09397500
09397800
09398000
09398500
09399000
Relation characteristic L H D 0 U
0
-
0
-
-
0
-
0
0
0
1
0
1
0
0
0
1
0
1
-
-
0
1
1
1
-
0
1
0
1
1
0
-
1
-
-
0
-
0
0
0
0
1
1
0
0
0
0
0
1
-
-
0
0
0
0
-
0
0
0
0
0
0
-
0
-
-
0
-
0
0
0
0
0
0
0
0
0
0
0
1
-
-
0
0
0
0
-
1
0
1
1
0
0
-
0
-
-
0
-
0
0
0
0
0
0
0
0
0
0
0
0
-
-
0
0
0
0
-
0
0
0
0
0
0
1
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
1
0
0
0
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
56
____
2567
2
44244
121920424611
10711484585242425150
2993031091104704692224
3,0002,990
29
1342,0502,040
7877
2,5502,520
197192
92,7502,720
145147
2,4202,4102,9502,9302,6002,590
5
2635
1817090
15
27442474
86102143184319
37
257439
2,0302,220
6261
127118517649250286
1,6301,610
194219
5,6905,700
143
5705,3805,310
172162
4,4404,410
373330
487,5007,090
314406
6,2706,2307,1706,9107,5107,370
10
5780
443256294
31
591,5701,600
202243357383793
616
411744
3,2603,730
7589
208196702
1,020382488
3,0902,980
544565
7,9908,190
335
9738,4508,240
259242
5,8905,970
524463
12012,50011,500
464746
10,70010,60011,20010,60013,60013,200
25
126160
9201,0601,050
57
Ill6,2606,000
405613787818
1,5301126
6812,0205,4707,850
92162358309988
2,550598
1,1106,0405,2401,5201,250
11,50013,000
569
1,65013,20012,600
401341
7,9109,250
754607
20521,30016,800
6971,790
19,40018,70017,90015,30026,50023,600
second) for (years)
50
207269
1,3902,7302,500
79
15815,60014,300
5981,1101,4201,3202,740
1742
9462,4307,670
10,200106183512457
1,2402,870
7961,3109,2508,4702,8402,27014,50016,600
806
2,46017,10017,300
530482
9,954012,000
956850
27929,80026,100
9012,160
29,00028,70024,00022,30041,50038,800
100
318381
2,0606,4705,910
108
21935,80033,200
8621,9002,2102,0003,620
2449
1,2801,690
10,50011,100
119136712685
1,5401,9401,0301,150
13,50013,3004,8504,55018,00018,600
914
3,08021,50021,700
682667
11,30012,2001,1901,150
29240,30039,4001,1301,490
41,90041,90031,10030,80062,90062,200
Maximum peak discharge
of record (cubic feet per second)
69
430
2,540
21
1
30,000
22
437
612
9
700
16,000
101
326
1,320
660
5,550
530
25,000
140
1,360
12,000
437
7,680
743
120
19,900
666
33,600
19,700
50,000
Basin, Climatic, and Flood Characteristics 171
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09399250
09400100
09400200
09400290
09400300
09400530
09400560
09400565
09400580
09400590
09400595
09400600
09400650
09400655
09400680
09400730
09400910
09401210
09401220
09401245
09401300
09401370
09402100
09403930
09404050
09424200
09424407
09424410
09424430
09424470
09424480
Station name
Jacks Canyon Tributary No. 2near Winslow, Ariz.
Ganado Wash Tributary nearGanado, Ariz.Steamboat Wash Tributary nearGanado, Ariz.Teshbito Wash Tributary nearHoUbrook, Ariz.Teshbito Wash near Holbrook, Ariz.
Cow Canyon near Winslow, Ariz.
Oraibi Wash Tributary nearOraibi, Ariz.Folacca Wash Tributary nearChinle, Ariz.
Castle Butte Wash near Winslow,Ariz.Rio de Flag at Hidden Hollow Roadat Flagstaff, Ariz.
Schultz Canyon at Flagstaff, Ariz.
Rio de Flag at Flagstaff, Ariz.
Sinclair Wash at Flagstaff, Ariz.
Rio de Flag at 140 at Flagstaff,Ariz.Switzer Canyon at Flagstaff, Ariz.
Lockett Fanning Diversion atFlagstaff, Ariz.
Fay Canyon near Flagstaff, Ariz.
Slate Mountain Wash nearFlagstaff, Ariz.
Cedar Wash near Cameron, Ariz.
Klethla Valley Tributary nearKayenta, Ariz.
Hamblin Wash Tributary nearCedar Ridge, Ariz.
Hamblin Wash Tributary No. 2near Tuba City, Ariz.Forest Boundary Wash near Cameron,Ariz.
West Cataract Creek near Williams,Ariz.Spring Valley Wash Tributary, nearWilliams, Ariz.Cottonwood Wash No.l near Kingman,Ariz.McGarrys Wash near Kingman, Ariz.
Big Sandy River Tributary nearKingman, Ariz.
Kaiser Spring Canyon Tributarynear Wikieup, Ariz.Kirkland Creek near Kirkland,Ariz.
Ash Creek near Kirkland, Ariz.
Flood region
11
11
11
11 '
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
12
12
12
12
12
12
Lati
tude, in decimal degrees
34.
35.
35.
35.
35.
35.
35.
36.
35.
35.
35.
35.
35.
35.
35.
35.
35.
35.
35.
36.
36.
36.
35.
35.
35.
35.
35.
35.
34.
34.
34.
765
711
764
481
449
100
872
047
325
242
227
222
164
184
212
222
135
515
859
498
349
055
924
248
574
181
117
092
572
394
453
Longi
tude, in decimal degrees
111
109
109
110
110
110
110
110
110
111
111
111
111
111
111
111
111
111
111
110
111
111
111
112
112
113
113
113
113
112
112
.012
.497
.800
.087
.068
.987
.556
.081
.422
.684
.658
.657
.680
.632
.639
.599
.630
.835
.442
.621
.504
.393
.737
.224
.153
.469
.650
.658
.478
.722
.796
System
atic Drainage years area, in of square
record miles
14
14
12
14
14
15
14
13
13
13
11
18
11
13
12
12
16
14
10
15
14
13
14
13
14
15
12
16
16
10
16
31.80
11.10
0.32
16.40
57.40
3.53
1.78
6.17
5.53
31.50
6.09
51.00
8.16
82.40
1.87
1.05
2.76
5.43
556.00
0.77
0.10
2.16
0.72
3.18
3.93
143.00
13.50
1.99
1.70
109.00
6.95
Mean basin eleva
tion, in
feet
6,530
6,770
6,750
6,420
6,280
6,020
6,890
5,820
8,130
8,060
8,050
7,200
7,840
7,130
8,020
7,000
7,350
6,430
6,730
5,860
4,670
6,810
7,190
6,750
5,350
4,610
3,700
3,520
--
4,680
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
19.2
11.8
12.1
8.2
9.2
10.0
10.2
12.3
8.6
25.4
21.9
25.3
22.5
20.0
19.9
20.0
19.6
19.7
13.7
10.2
7.6
6.0
11.9
23.5
12.2
14.0
12.0
12.0
11.2
--
10.4
53.8
51.4
53.8
54.0
53.7
55.5
54.9
55.0
55.0
44.2
44.1
44.1
44.2
44.1
44.1
44.1
44.2
51.0
55.3
54.4
55.0
55.0
55.3
49.6
52.2
53.9
60.5
61.0
60.9
54.6
54.7
172 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09399250
09400100
09400200
09400290
09400300
09400530
09400560
09400565
09400580
09400590
09400595
09400600
09400650
09400655
09400680
09400730
09400910
09401210
09401220
09401245
09401300
09401370
09402100
09403930
09404050
09424200
09424407
09424410
09424430
09424470
09424480
Relation characteristic L H D 0 U
- - - - 1
11000
- - - - 1
00100
10100
10000
- - - - 1
10100
10000
- - - - 1
- - - - 1
00000
10000
- - - - 1
00100
- - - - 1
00000
- - - - 1
10000
10000
- - - - 1
- - - - 1
- - - - 1
00100
10000
10100
- - - - 1
10000
- - - - 1
- - - - 1
00000
Peak discharge (cubic indicated recurrence
2
- ___
222238234
-
13369362652642
6464
37361352
8585
221____
8017247374
_
4013838
279
10
741,5001,490
121118
____
6-
42-
2126271819
3,6803,640-___
2111819
57----
786132132
5
--_-
902533528
69873831
1,0501,080
128149
180708647288297
897
35874
222167218
1,54096
112
1342657
____
3354,5504,540
193180
36
200____
10896
1236197
5,8605,650
8238097
218
457464
10
---_
1,750820846
____
1601,3101,2901,3401,600
182279
407995939540591
1,170
497158433261356
1,930152185
19947
111____
6288,0708,110
244247
91
452
258183253114224
7,3207,090
1,460174251
412
887900
feet per interval
25
--__
2,9701,3101,450
2721,9702,0501,7302,990
261660
6921,4101,3601,0401,160
2,000
845349
1,420424768
3,280245370
33888
333
1,07014,80014,200
313380
155
768
438350584217618
9,14010,300
2,700399653
813
1,8201,790
second) for (years)
50
____
4,4901,7802,000
3752,5102,7702,0403,680
327758
9891,7701,8401,5901,690
3,020
1,240580
1,700583981
5,060331471
478132380
1,56021,90022,100
366461
209
1,100
614524763326741
10,50014,800
4,810686
1,170
1,330
2,9003,040
100
____
5,8102,3502,400
4033,0903,1702,3502,850
400507
1,1402,1502,1702,3202,310
3,900
1,500910
1,200780887
6,780430462
539190248
1,88031,00031,100
421442
214
1,280
682744795465565
11,80020,200
7,3801,1201,880
2,050
4,4304,700
Maximum peak discharge
of record (cubic feet per second)
9,330
1,680
383
890
1,580
253
383
1,130
860
153
48
240
401
421
135
85
87
88
10,400
290
110
350
115
151
190
7,000
1,000
353
1,310
1,000
4,000
Basin, Climatic, and Flood Characteristics 173
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09424700
09424900
09425500
09468300
09468500
09489100
09489499
09489700
09490500
09492400
09494000
09494300
09496000
09496500
09496600
09496700
09496800
09497800
09497900
09497980
09498600
09498800
09498870
09498900
09499000
09501300
09502700
09502800
09503000
09503720
09503740
Flood Station name region
Iron Spring Wash Tributary nearBagdad, Ariz.Santa Maria River near Bagdad,Ariz.Santa Maria River near Alamo,Ariz.SevenmiLe Wash Tributary nearGlobe, Ariz.San Carlos River near Peridot, Ariz.
Black River near Maverick, Ariz.
Black River above Willow Creek Diversion near Point of Fines, Ariz.
Big Bonito Creek near Fort Apache,Ariz.Black River near Fort Apache, Ariz.
East Fork White River near FortApache, Ariz.
White River near Fort Apache, Ariz.
Carrizo Creek above Corduroy Creeknear Show Low, Ariz.Corduroy Creek near mouth nearShow Low, Ariz.
Carrizo Creek near Show Low, Ariz.
Cibecue 1 Tributary to Carrizo Creeknear Show Low, Ariz.
Cibecue 2 Tributary to Carrizo Creeknear Show Low, Ariz.Carrizo Creek Tributary near Show Low,Ariz.Cibecue Creek near Chrysotile, Ariz.
Cherry Creek near Young, Ariz.
Cherry Creek near Globe, Ariz.
Cristopher Creek Tributary nearKohl's Ranch, Ariz.Tonto Creek near Gisela, Ariz.
Rye Creek near Gisela, Ariz.
Gold Creek near Payson, Ariz.
Tonbo Creek above Gun Creek,near Roosevelt, Ariz.Tortilla Creek at Tortilla Flat,Ariz.Crookton Wash near Seligman, Ariz.
Williamson Valley Wash near Paulden,Ariz.Granite Creek near Frescott, Ariz.
Hell Canyon near Williams, Ariz.
Hell Canyon Tributary near Ash
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
Lati
tude , in decimal degrees
34
34
34
33
33
33
33
33
33
33
33
34
34
33
33
33
33
33
34
33
34
34
34
34
33
33
35
34
34
35
35
.522
.306
.300
.586
.296
.707
.481
.667
.713
.822
.736
.000
.018
.985
.991
.988
.954
.843
.083
.828
.322
.129
.033
.003
.980
.527
.287
.867
.567
.160
.084
Longi
tude , in decimal degrees
113.112
113.346
113.517
110.650
110.451
109.447
109.752
109.846
110.211
109.814
110.166
110.289
110.242
110.280
110.324
110.311
110.331
110.557
110.924
110.856
111.067
111.255
111.292
111.358
111.303
111.387
112.732
112.612
112.450
112.210
112.408
System
atic Drainage years area, in of square
record miles
15
19
28
16
57
20
33
24
30
28
29
14
24
36
14
14
14
28
16
21
11
11
20
15
46
18
17
21
16
13
10
0.
1,210.
1,520.
0.
1,027,
315,
560,
119,
1,232.
38.
632
225,
203,
439
0,
0,
2,
295
62,
200,
0,
430,
122,
6.
675,
24.
6.
255,
39.
14.
0.
,64
,00
,00
,83
.00
.00
.00
.00
,00
.80
.00
.00
.00
.00
.10
.06
.55
.00
.10
.00
.66
.00
.00
.44
.00
,30
.00
.00
.60
,90
,75
Mean basin eleva
tion, in
feet
3,470
4,010
3,650
4,410
4,480
8,700
8,000
7,920
7,200
8,580
7,400
6,370
6,370
6,320
5,390
5,240
5,810
5,700
6,030
5,600
6,080
5,810
4,390
4,590
5,020
2,690
5,970
5,120
5,900
7,110
5,180
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
12.1
14.0
14.4
19.0
17.2
27.2
25.3
27.9
23.4
31.2
25.4
22.5
21.7
22.0
18.0
18.0
20.0
20.7
24.8
24.0
29.0
24.7
24.2
21.0
23.9
15.0
15.5
17.3
22.1
24.1
17.2
54.8
62.6
63.3
53.1
58.2
40.4
44.1
44.4
47.9
40.7
47.3
44.7
44.0
44.7
44.6
44.7
44.6
45.7
44.5
47.5
45.0
46.2
54.5
57.1
57.3
65.0
52.7
52.2
54.0
46.9
50.4Fork, Ariz.
174 Methods for Estimating Magnituda and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09424700
09424900
09425500
09468300
09468500
09489100
09489499
09489700
09490500
09492400
09494000
09494300
09496000
09496500
09496600
09496700
09496800
09497800
09497900
09497980
09498600
09498800
09498870
09498900
09499000
09501300
09502700
09502800
09503000
09503720
09503740
Relation characteristic L H D 0 U
0
1
1
1
1
0
0
0
0
0
0
-
1
1
0
1
0
1
0
1
0
0
0
1
0
1
1
0
1
-
0
0
0
0
0
0
0
0
0
0
1
0
-
0
0
0
0
0
1
0
0
1
0
1
0
0
0
0
0
1
-
0
0
1
1
0
0
1
0
0
1
0
0
-
1
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
-
0
0
0
0
0
0
0
0
0
0
1
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
Peak discharge (cubic indicated recurrence
2
1213
7,3107,2703,2503,260
2727
7,4407,4201,6001,6002,2102,210
622624
6,8606,840
274275
3,4003,390____
1,2401,0501,0503,1903,180
44434342
283280
4,3604,3401,3801,3702,1902,180
3030
4,8104,7502,9802,960
310307
11,40011,4001,9401,920
79
1,3001,300
837831
-
2251011
5
6369
13,80014,3009,86010,700
134133
15,20015,2003,8404,0005,3905,5701,4301,550
19,80019,500
508562
6,1006,330
5,0703,6303,7107,4307,460
92846963
657607
8,0107,9003,1103,0105,3205,290
6973
11,30010,8006,2506,040
792759
26,40025,8004,2904,020
86120
4,0704,2301,8501,820
7543244
10
147168
18,80021,60017,60021,000
299281
22,30022,6006,2606,9308,7009,5002,2202,780
33,50031,900
7201,0108,3909,620
8,2207,0607,19011,90012,000
1341098974
1030849
11,00010,9004,7104,4008,5208,400
111135
18,30016,4009,5708,8101,3001,180
40,10037,5006,2905,360
313435
7,4007,9402,7902,760
1,31058
115
feet per interval
25
357403
25,60036,60032,90042,600
686575
33,70035,60010,80013,00014,60017,5003,5505,730
57,80050,9001,0702,27011,90017,100
14,10014,50013,90020,00020,500
200152118102
1,6701,22015,20016,1007,2906,81014,20014,000
188296
31,60025,60015,50013,4002,2301,940
62,00053,3009,2707,0501,2401,360
14,00015,2004,3504,610
2,440108307
second) for (years)
50
629631
31,10044,60049,20055,5001,150
86444,10045,30015,50018,50020,60024,0004,8209,28081,50062,6001,3904,11015,00022,700
20,10023,30021,00028,40028,200
25915714295
2,2901,72018,80021,4009,62010,20019,80019,900
269438
45,70033,50021,50019,1003,1603,050
81,60065,10011,8009,9403,0202,730
21,00022,4005,7807,310
4,220161483
100
1,040975
36,70055,60070,80073,4001,8201,310
56,20057,50021,70025,30028,10032,1006,34013,300
110,00079,8001,7906,26018,60029,500
27,40035,80030,30039,10037,900
326193168112
3,0502,46022,70027,90012,30014,30026,80027,300
374655
64,40044,50029,30026,4004,3304,540
104,00081,10014,50013,7006,7004,890
30,30031,3007,47010,600
6,430231740
Maximum peak discharge
of record (cubic feet per second)
180
23,100
33,600
640
40,600
14,000
17,900
4,510
50,000
2,700
14,00
10,000
10,900
23,000
165
120
1,260
22,200
7,290
15,700
265
38,000
44,400
2,800
61,400
7,500
480
14,800
6,660
1,080
84
Basin, Climatic, and Flood Charactaristics 175
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09503750
09503800
09504100
09504400
09504500
09504800
09505200
09505220
09505250
09505300
09505350
09505600
09505800
09505900
09507600
09507700
09507980
09508300
09510070
09510080
09510100
09510150
09510170
09510180
09510200
09512100
09512200
09512300
09512420
09512500
09512700
Flood Station name region
Limestone Canyon near Faulden,Ariz.
Volunteer Wash near Bellemont,Ariz.Hull Canyon near Jerome , Ariz .
Munds Canyon Tributary nearSedona, Ariz.
Oak Creek near Cornville, Ariz.
Oak Creek Tributary nearCornville, Ariz.
Wet Beaver Creek near Rimrock,Ariz.Rocky Gulch near Stoneman Lake,Ariz. (USFS)
Red Tank Draw near Rimrock,Ariz.
Rattlesnake Canyon near Rimrock,Ariz.Dry Beaver Creek near Rimrock,Ariz.Dirty Neck Canyon near Clints Well,Ariz.
West Clear Creek near Camp Verde,Ariz.
Cottonwood Wash near Camp Verde,Ariz.East Verde River near Pine, Ariz.
Webber Creek above West Fork WebberCreek, near Pine, Ariz.
East Verde River near Childs, Ariz.
Wet Bottom Creek near Childs, Ariz.
West Fork Sycamore Creek aboveMcFarland Creek, near Sunflower, Ariz.
West Fork Sycamore Creek nearSunflower, Ariz.
East Fork Sycamore Creek nearSunflower, Ariz.
Sycamore Creek near Sunflower, Ariz.
Camp Creek near Sunflower, Ariz.
Rock Creek near Sunflower, Ariz.
Sycamore Creek near Fort McDowell,Ariz.Indian Bend Wash near Scottsdale,Ariz.Salt River Tributary in SouthMt. Park, at Phoenix, Ariz.
Cave Creek near Cave Creek, Ariz.
Lynx Creek Tributary near Prescott,Ariz.Agua Fria River near Mayer, Ariz.
Agua Fria River Tributary No 2 near
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
Lati
tude, in decimal degrees
34
35
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
33
33
33
33
33
33
33
33
33
33
34
34
34
.980
.151
.739
.922
.766
.712
.675
.747
.695
.767
.729
.512
.539
.506
.392
.411
.283
.161
.961
.946
.949
.851
.760
.730
.694
.539
.347
.783
.547
.315
.033
Longi
tude, in decimal degrees
112 .401
111.898
112
111
111
111
111
111
111
111
111
111
111
111
111
111.
111.
Ill
111
111,
111.
Ill,
111,
111,
111,
111,
112.
112.
112.
112.
112.
.143
.644
.890
.881
.671
.494
.714
.673
.775
.358
.693
.753
.268
.372
.647
.692
.487
.485
,461
,452
,496
,508
,541
.916
084
007
399
063
145
System
atic Drainage years area, in of square
record miles
11
14
18
16
45
15
25
24
21
23
26
12
21
14
13
16
25
19
14
15
23
15
17
10
27
10
26
28
10
47
18
14.50
131.00
0.91
1.19
357.0
0.04
111.00
1.40
49.40
24.60
142.00
3.42
241.00
0.64
6.65
4.92
328.00
36.40
4.58
9.80
4.49
52.30
2.60
15.20
164.00
139.00
1.75
121.00
0.95
588.00
1.11
Mean basin eleva
tion, in
feet
5,310
7,620
7,050
6,880
6,200
3,570
6,410
7,190
5,910
6,560
6,220
7,140
6,680
3,540
6,430
6,980
5,140
4,810
5,430
5,260
5,760
4,260
3,520
3,680
3,820
1,780
1,730
3,470
5,900
5,000
2,140
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
15.5
25.7
22.0
26.0
22.6
12.4
24.8
25.0
21.6
22.8
23.1
26.0
23.4
14.5
30.0
27.5
24.7
25.0
24.5
24.5
24.5
23.5
20.0
16.0
21.2
10.9
9.0
15.7
16.0
16.7
16.2
50.6
44.0
52.4
44.2
51.9
52.8
50.4
44.3
50.6
46.6
51.3
44.0
51.8
53.1
44.6
44.0
54.5
57.8
58.0
58.3
58.2
60.0
63.1
64.1
65.0
65.6
65.6
62.2
54.2
60.9
60.2Rock Springs, Ariz.
176 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09503750
09503800
09504100
09504400
09504500
09504800
09505200
09505220
09505250
09505300
09505350
09505600
09505800
09505900
09507600
09507700
09507980
09508300
09510070
09510080
09510100
09510150
09510170
09510180
09510200
09512100
09512200
09512300
09512420
09512500
09512700
Relation characteristic L H D 0 U
1
0
1
0
0
-
1
0
1
1
1
-
1
0
0
0
0
1
0
1
0
0
0
0
0
1
0
1
-
1
1
0
0
1
0
0
-
0
1
1
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
1
0
0
0
1
-
0
0
0
0
0
-
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
-
0
1
0
0
0
0
0
-
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
273272353362
23
7373
5,0004,980____
i;
3,2803,260
4545
717714865859
4,8504,820
894,8504,810
2323
2822798889
3,2003,1901,7301,710
353699
1003738
1,0301,020
116115497491
2,2702,260
3753871919
1,7301,720-
405,8505,830
307304
5
901889
1,1601,410
2332
232222
12,00011,800
176,4506,210
152152
1,8501,8501,8801,820
10,50010,000
2749,8309,450
7580
948884289296
9,3309,1704,6504,370
267279516529188201
4,0203,810261264
1,3401,2807,5907,4101,4402,130
184191
4,3104,300
12210,20010,200
564529
10
1,7101,6102,0603,080
67103413367
18,30017,400
____
348,8208,090
297292
3,1103,1102,7602,57015,70013,800 -
49414,00012,700
142165
1,8301,500
549573
16,30015,3007,5306,350
717702
1,2101,180
446488
8,2706,920
394435
2,1702,00014,00012,9002,9605,640
531536
6,9106,920- -
22813,90014,300
785681
25
3,4202,9603,7006,860
189304749619
28,30025,700
____
7612,00010,700
629594
5,5205,5404,1003,820
23,70018,400 -
96320,40017,700
282369
3,7602,4701,1101,170
29,60025,30012,3008,7501,9501,5803,0002,5101,1401,180
18,00011,800
603838
3,5503,310
26,70021,7006,50013,2001,5001,330
11,40011,600
____
46219,30021,800
1130942
second) for (years)
50
5,4004,9205,31011,100
351507
1,090879
36,90032,600
____
5314,40014,2001,040
9338,0808,7705,2405,620
30,90023,300
1,60025,80022,700
441564
6,0603,7401,7501,960
43,60034,70016,60011,8003,6302,6905,3504,2902,1002,110
29,80017,700
7901,4204,8205,480
40,20030,70010,90023,1002,7902,31015,60017,300
68224,00028,2001,4301,290
100
8,1707,4607,26016,000
597801
1,5101,270
46,60041,300
____
6116,80018,5001,6401,430
11,50012,8006,5107,910
39,00029,900 -
2,47031,70029,200
663853
9,3605,5902,6703,030
61,50046,90021,60016,0006,2104,2709,0006,7603,6603,450
47,00026,1001,0002,1806,2808,180
57,80042,70017,40034,1004,7403,720
20,70024,200
1,03029,30036,0001,7901,830
Maximum peak discharge
of record (cubic feet per second)
4,100
2,300
500
705
26,400
53
10,900
1,550
10,500
4,000
26,600
210
22,400
250
2,820
1,220
23,500
6,830
1,700
3,480
1,940
16,100
402
1,900
24,200
21,000
670
12,400
820
33,100
1,200
Basin, Climatic, and Flood Characteristics 177
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09512800
09513780
09513800
09513820
09513835
09513860
09513890
09513910
09513970
09515500
09515800
09516500
09516600
09516800
09428545
09428550
09428800
09470500
09470900
09471000
09471080
09471087
09471090
09471120
09471140
09471170
09471185
09471195
09471200
09471550
09471600
Flood Station name region
Agua Fria River near Rock Springs,Ariz.New River near Rock Springs, Ariz.
New River at New River, Ariz.
Deadman Wash near New River, Ariz.
New River at Bell Road, nearFeoria, Ariz.
Skunk Creek near Phoenix, Ariz.
New River at Peoria, Ariz.
New River near Glendale, Ariz.
Agua Fria River at Avondale, Ariz.
Hassayampa River at Box Damsitenear Wickenburg, Ariz.
Hartman Wash near Wickenburg, Ariz.
Hassayampa River near Morristown,Ariz.Ox Wash near Morristown, Ariz.
Jack Rabbit Wash near Tonopah,Ariz.Cunningham Wash Tributary nearWenden, Ariz.Bouse Wash Tributary near Bouse,Ariz.Tyson Wash Tributary near Quartzsite,Ariz.San Pedro River at Palominas, Ariz.
San Pedro River Tributary nearBisbee, Ariz.
San Pedro River at Charleston,Ariz.
Walnut Gulch 63.010 near Tombstone,Ariz.: USDAWalnut Gulch 63.111 near Tombstone,Ariz.: USDA
Walnut Gulch 63.009 near Tombstone,Ariz. : USDA
Walnut Gulch 63.011 near Tombstone,Ariz.: USDA
Walnut Gulch 63.006 near Tombstone,Ariz. : USDAAgricultural Research ServiceWatershed W-IV near Tombstone, Ariz.
Walnut Gulch 63.103 near Tombstone,Ariz. : USDA
Walnut Gulch 63.007 near Tombstone,Ariz. : USDAWalnut Gulch near Fairbank, Ariz.
San Pedro River near Tombstone,Ariz.Canary Wash near Benson, Ariz.
12
12
12
12
12
12
12
12
12
12
12
12
12
12
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
Lati
tude, in decimal degrees
34
33
33
33
33
33
33
33
33
34
33
33
33
33
34
33.
33
31
31
31.
31.
31,
31
31.
31,
31.
31.
31.
31.
31.
31.
.014
.974
.911
.842
.638
.729
.595
.537
.435
.045
.963
.885
.883
.659
.007
.901
.512
.380
.570
.626
.720
.734
,718
,741
,724
739
,742
,733
,729
751
876
Longi
tude, in decimal degrees
112.167
112.098
112.141
112.144
112.239
112.120
112.262
112.281
112.333
112.709
112.828
112.661
112.650
112.828
113.578
113.974
114.217
110.111
110.027
110.174
110.025
109.948
110.024
109.994
110.055
110.044
110.054
110.097
110.153
110.201
110.342
System
atic Drainage years area, in of square
record miles
17
25
22
20
21
26
12
21
23
38
16
30
17
16
13
14
14
48
16
71
15
20
15
19
20
24
19
16
25
20
14
1,130,
67,
83,
11,
187,
64,
317
323,
633,
417,
5,
774.
6.
137,
0,
14,
13,
741.
5.
1,219.
6,
0.
9.
3.
36.
0.
0.
5.
57.
1,740.
0.
.00
.30
.30
.10
.00
.60
.00
.00
.00
.00
.57
.00
.31
.00
.77
.60
.70
,00
,25
,00
.42
,22
,11
18
70
87
.01
22
70
00
79
Mean basin eleva
tion, in
feet
4,770
3,970
3,600
1,980
2,700
2,180
2,320
2,130
4,750
2,690
3,190
2,290
2,260
2,330
1,230
1,520
4,950
4,840
4,970
5,020
4,840
4,880
4,790
4,550
4,500
4,480
4,700
4,820
5,240
Mean annual precipi tation,
in inches
16.6
20.0
19.5
11.0
15.6
12.2
13.3
13.8
16.3
19.3
11.0
16.9
12.2
9.2
8.1
6.5
6.0
17.9
16.0
16.5
14.0
14.0
14.0
14.0
14.0
14.0
14.0
14.0
14.0
16.2
15.0
Mean annual evapor
ation, in
inches
60.5
60.4
60.7
62.3
65.2
65.2
65.2
65.3
65.3
58.6
60.5
60.8
60.7
61.4
65.2
65.7
75.1
65.2
65.0
65.4
64.9
64.7
64.9
64.8
65.0
64.9
64.9
65.0
65.1
65.5
62.8
178 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09512800
09513780
09513800
09513820
09513835
09513860
09513890
09513910
09513970
09515500
09515800
09516500
09516600
09516800
09428545
09428550
09428800
09A70500
09A70900
09A71000
09A71080
09A71087
09A71090
09471120
09471140
09471170
09471185
09471195
09471200
09471550
09471600
Relation characteristic L H D 0 U
0
1
1
-
1
1
1
1
-
0
1
1
1
-
1
1
-
1
1
1
1
1
1
0
1
0
1
0
1
1
-
0
0
0
-
0
0
0
0
-
0
0
0
0
-
0
0
-
0
0
1
0
0
0
0
0
0
0
0
0
0
-
1
0
0
-
1
1
0
1
-
0
0
0
0
-
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
-
0
0
0
0
-
0
0
0
0
-
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Peak discharge (cubic feet per indicated recurrence interval
2
7,4407,3902,3802,3603,1203,100
1871,9001,890
916913
2,8002,7801,4001,400
2,3763,1703,160
216215
2,8002,800
192191
9075268
344398
5175,9205,630
451415
6,7606,540
36436011298
590544530464
1,4601,320
707899
263276
1,7401,6107,4306,760
107
5
22,80022,2006,5806,3007,8607,490
9746,5006,4603,5103,4909,3009,2908,2008,320
8,4808,490
794767
7,5007,960
661658
5,220101150998
1,090
1,2509,3309,030
903863
12,10011,800
771793223196
1,5701,4101,6901,4202,6602,500
2422481615
1,090997
3,6803,43011,90011,200
255
10
42,20038,10011,1009,78012,70011,100
1,79011,90011,5007,0406,75016,00015,80015,00015,300
14,00014,0001,5701,410
12,70014,7001,2501,230
8,950141254
1,7301,860
1,97012,00011,7001,2601,240
17,30016,6001,1501,230
321266
2,5502,1502,8802,1503,6703,480
4574452019
2,2501,8205,4504,95015,40014,800
394
25
83,30062,90019,10014,40021,10015,800
3,30021,80019,80014,80012,70023,00024,60023,00024,800
23,50023,4003,2302,530
22,30028,9002,4602,320
15,300199420
3,0703,170
3,16015,70015,8001,7801,850
26,10024,8001,7901,970
474380
4,1903,3804,8203,3405,2005,120
8958052725
4,7803,4008,3207,500
20,40020,600
622
second) for (years)
50
131,00080,00027,10019,80029,20021,500
6,16031,80028,90023,80020,20029,00034,60030,00035,000
32,60031,9005,1504,070
32,20040,2003,7903,930
24,600247553
4,4404,410
4,25018,90019,4002,1902,390
34,80032,9002,3802,640
610483
5,7104,5506,5504,4506,5306,6201,3701,170
3229
7,7105,15011,0009,900
24,60025,600
817
100
199,000108,00036,90026,90039,10029,100
9,61044,10040,00036,50030,00035,00046,10037,00046,500
43,70042,4007,8206,190
45,00054,1005,5706,040
35,000300717
6,1705,990
5,65022,30023,4002,6203,030
45,70042,9003,0803,470
766609
7,4906,0008,4705,7708,0308,4202,0201,670
3833
11,8007,60014,00012,70029,20031,300
1,070
Maximum peak discharge
of record (cubic feet per second)
59,500
18,600
19,500
1,850
14,600
11,500
20,000
38,000
29,300
58,000
2,600
47,500
2,900
6,840
173
2,920
1,950
22,000
1,460
98,000
2,220
541
2,640
4,390
6,590
1,270
31
2,590
11,500
24,200
84
Basin, Climatic, and Flood Characteristics 179
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09471700
09472100
09472400
09473000
09473200
09473600
09478200
09478500
09478600
09479200
09480000
09480500
09481500
09481700
09481750
09481800
09481900
09482330
09482420
09482480
09483030
09483040
09483100
09483200
09484000
09484200
09484500
09484510
09484560
09484570
09484580
Station name
Fenner Wash near Benson, Ariz.
Peck Canyon Tributary nearRedington, Ariz.
Mammoth Wash near Mammoth, Ariz.
Aravaipa Creek near Mammoth, Ariz.
Green Lantern Wash near Winkelman,Ariz.
Tarn O'Shanter Wash near Hayden,Ariz.Durham Wash near Florence, Ariz.
Queen Creek at Whitlow Damsitenear Superior, Ariz.Queen Creek Tributary No 3 atWhitlow Dam, Ariz.Queen Creek Tributary at ApacheJunction, Ariz.
Santa Cruz River near Lochiel,Ariz.
Santa Cruz River near Nogales,Ariz.Sonoita Creek near Patagonia,Ariz.
Calabasas Canyon near Nogales,Ariz.Sopor i Wash at Amado, Ariz.
Demetrie Wash Tributary nearContinental, Ariz.
Ocotillo Wash near Continental,Ariz.Pumping Wash near Vail, Ariz.
Julian Wash at Tucson, Ariz.
Big Wash at Tucson, Ariz.
Anklam Wash at Tucson, Ariz.
West Speedway Wash near Tucson,Ariz.Tanque Verde Creek near Tucson,Ariz.
Agua Caliente Wash Tributarynear Tucson, Ariz.Sabino Creek near Tucson, Ariz.
Bear Creek near Tucson, Ariz.
Tanque Verde Creek at Tucson,Ariz.
Ventana Canyon Wash near Tucson,Ariz.Cienega Creek near Pantano, Ariz.
Mescal Arroyo near Pantano, Ariz.
Barrel Canyon near Sonoita, Ariz.
Flood region
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
Lati
tude , in decimal degrees
31.
32.
32,
32,
32,
33,
32,
33.
33,
33
31,
31
31
31
31
31
31
32,
32
32
32
32
32
32
32
32
32
32,
31,
31
31.
,980
,487
.676
.844
.925
.029
.722
.299
.292
.404
.355
.344
.500
.457
.724
.871
.833
.069
.171
.186
.225
.239
.247
.269
.317
.306
.265
.310
.986
.990
.862
Longi
tude , in decimal degrees
110.
110.
110,
110,
110
110
111,
111
111,
111
110
110
110
110
111
111
111
110
110
111
111
111
110
110
110
110
110
110
110
110
110
,216
,500
.685
.619
.726
.873
.108
.274
.281
.541
.589
.851
.817
.986
.061
.087
.000
.806
.940
.002
.031
.045
.679
.737
.810
.801
.841
.839
.566
.564
.690
System
atic Drainage years area, in of square
record miles
16
14
14
36
13
15
19
17
14
19
38
56
43
14
19
14
10
16
12
17
17
17
26
16
55
15
22
17
14
17
15
2.71
8.02
2.40
541.00
3.63
4.37
15.60
144.00
0.37
0.51
82.20
533.00
209.00
10.30
176.00
0.15
3.60
0.54
26.50
2.75
2.11
0.46
43.00
2.04
35.50
16.30
219.00
6.46
289.00
38.40
14.10
Mean basin eleva
tion, in
feet
4,180
3,680
3,700
4,530
2,590
3,050
3,670
3,180
2,320
1,760
5,150
4,850
4,800
4,360
3,840
3,620
3,280
2,900
2,850
2,700
2,750
4,780
3,300
6,300
5,860
4,340
4,600
4,890
4,260
5,000
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
12.3
11.7
13.8
16.2
14.0
15.6
12.1
17.9
12.0
10.5
18.2
18.7
19.3
15.8
15.5
14.5
14.1
11.2
11.0
11.0
11.8
11.8
17.0
14.0
22.6
20.6
16.7
13.0
16.6
15.0
16.0
65.1
64.7
70.6
65.0
64.5
64.0
64.9
65.0
65.0
65.0
60.3
61.0
61.0
63.1
65.0
65.0
65.0
61.9
64.8
65.0
65.2
64.8
59.2
59.4
59.7
59.7
60.1
60.1
59.8
59.8
65.2
180 Methods for Estimating Magnitude snd Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09471700
09472100
09472400
09473000
09473200
09473600
09478200
09478500
09478600
09479200
09480000
09480500
09481500
09481700
09481750
09481800
09481900
09482330
09482420
09482480
09483030
09483040
09483100
09483200
09484000
09484200
09484500
09484510
09484560
09484570
09484580
Relation characteristic L H D 0 U
0
-
0
0
1
1
1
0
-
-
1
0
1
1
0
0
1
-
0
1
-
0
1
1
1
1
1
1
0
1
-
0
-
0
0
0
1
1
0
-
-
0
0
0
0
1
0
0
-
0
1
-
0
0
0
0
0
0
0
1
1
-
0
-
0
0
0
0
0
0
-
-
0
0
0
0
0
0
0
-
0
0
-
1
0
0
0
0
0
0
0
0
-
0
-
0
0
0
0
0
0
-
-
0
0
0
0
0
0
0
-
0
0
-
0
0
0
0
0
0
1
0
0
-
0
1
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
1
Peak discharge (cubic feet per indicated recurrence interval
2
192199
392162174
4,1003,920
499426365343554554
3,6103,100
67
821,5501,5104,2004,0703,1102,960
305346
2,2102,100
252962
132
8542151567
105----
1909187
1,5101,400
97120
1,1501,120366420
1,9201,910
146197
1,8501,930
743771
525
5
498507
950750671
8,1907,8701,3701,130
584615
1,3201,3208,8307,420
157
1943,0903,0607,7807,6005,3405,190
688809
4,6004,430
5765
338446
____
201814
1,120365410
459201196
3,1102,920
207275
2,6402,570
673874
5,3905,140201375
3,9904,2202,0502,050
1,260
10
809818
1,5001,5801,220
11,80011,2002,3201,700
762899
2,0702,08014,30010,900
238
2964,4904,480
10,90010,6007,2107,0601,0401,3306,8206,550
86103843912
3071,1401,890
803816
718296288
4,6504,270
311472
4,0403,880
9231,4409,1508,300
236672
6,1906,7003,6403,470
2,000
25
1,3401,340
2,4103,3502,26017,40016,5004,0702,7301,0301,3903,3503,360
24,30017,100
371
4646,7606,86015,70015,40010,10010,1001,6102,20010,40010,000
134163
2,2901,850
4821,6203,1301,7301,550
1,150435434
7,2806,590
486795
6,3106,0201,2902,37015,90013,700
2791,160
10,20010,9006,9606,100
3,210
second) for (years)
50
1,8601,820
3,2405,3203,370
22,30021,2005,8703,8001,2601,8104,5604,540
34,40023,500
479
6048,8609,030
20,00019,70012,60012,8002,1202,95013,80013,300
178211
4,4202,990
6292,0304,1802,7502,290
1,530551556
9,8408,840
6501,0708,3807,9901,6003,150
22,70018,900
3091,560
14,40014,80010,8008,890
4,310
100
2,4702,420
4,3207,9504,870
28,00026,8008,1405,1901,5202,3406,0306,030
47,20031,700
621
78811,30011,60024,90024,70015,40016,0002,7003,88017,80017,200
229269
8,0504,800
8212,4705,4704,0603,240
2,030675702
13,00011,700
8491,420
10,80010,3001,9404,120
31,00025,500
3392,050
19,80019,70016,30012,800
5,730
Maximum peak discharge
of record (cubic feet per second)
950
4,340
3,200
70,800
3,700
1,570
3,500
42,900
280
262
12,000
31,000
16,000
1,200
16,000
110
1,840
337
1,270
3,000
2,420
240
8,600
430
7,730
1,400
12,700
260
20,000
27,000
1,900
Basin, Climatic, and Flood Characteristics 181
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09484590
09484600
09485000
09485100
09485500
09485900
09485950
09486000
09486300
09486800
09487000
09487100
09487140
09487250
09487400
09488500
09488600
09514200
09517000
09517200
09517280
09517400
09519600
09519750
09519760
09519780
09520100
09520110
09520130
09520160
09520170
Flood Station name region
Davidson Canyon Wash near Vail,Ariz.Fantano Wash near Vail, Ariz.
Rincon Creek near Tucson, Ariz.
Saguaro Corners Wash near Tucson,Ariz.Fantano Mash at Tucson, Ariz.
Fima Wash near Tucson, Ariz.
Geronimo Wash near Tucson, Ariz.
Rillito Creek near Tucson, Ariz.
Canada del Oro near Tucson, Ariz.
Altar Wash near Three Points, Ariz.
Brawley Mash near Three Points,Ariz.Little Brawley Wash near Three Points,Ariz.San Joaquin Wash near Tucson, Ariz.
Los Robles Wash near Mar ana, Ariz.
Quijotoa Wash Tributary nearQuijotoa, Ariz.Santa Rosa Wash near Vaiva Vo, Ariz.
Silver Reef Mash near Casa Grande,Ariz.Waterman Wash near Buckeye, Ariz.
Hassayampa River near Arlington,Ariz.
Centennial Wash Tributary nearMenden, Ariz.Tiger Wash near Aguila, Ariz.
Winters Mash near Tonopah, Ariz.
Rainbow Wash Tributary nearBuckeye, Ariz.
Bender Wash near Gila Bend, Ariz.
Sauceda Wash near Gila Bend, Ariz.
Windmill Wash near Gila Bend,Ariz.Military Wash near Sentinel,Ariz.Hot Shot Arroyo near Ajo, Ariz.
Darby Arroyo near Ajo, Ariz.
Gibson Arroyo at Ajo, Ariz.
Rio Cornez near Ajo, Ariz.
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
Lati
tude , in decimal degrees
31.994
32.036
32.129
32.170
32.250
32.337
32.332
32.295
32.374
31.836
32.076
32.124
32.169
32.438
32.174
32.667
32.682
33.330
33.347
33.844
33.742
33.489
33.243
32.907
32.871
33.048
32.845
32.347
32.355
32.380
32.499
Longi
tude, in decimal degrees
110,
110,
110.
110,
110
110
110,
110,
111,
111,
111,
111,
111,
111
112
111,
111,
112,
112,
113,
113,
112.
112,
112.
112.
112.
113.
112.
112.
112.
112.
.644
.677
.626
.737
.850
.960
.944
.984
.009
.403
.337
.329
.133
.304
.108
.927
.834
.509
.725
.450
.279
.918
.637
,551
,758
,838
.279
.809
,825
,861
,881
System
atic Drainage years area, in of square
record miles
14
28
34
10
16
18
18
67
17
14
15
14
13
13
13
19
13
22
23
17
17
18
17
17
17
15
17
16
16
14
14
50
457
44
0
602
4
2
918
250
463
776
11
0
1,170
2
1,782
12
403
1,470
2
85
47
2
68
126
12
8
0
4
2
243
.50
.00
.80
.17
.00
.93
.08
.00
.00
.00
.00
.90
.45
.00
.44
.00
.80
.00
.00
.79
.20
.80
.43
.80
.00
.90
.70
.44
.72
.18
.00
Mean basin eleva
tion, in feet
4,340
4,500
4,850
3,040
4,560
4,430
3,600
4,400
4,000
3,920
3,710
2,800
2,530
3,350
2,800
2,340
1,620
1,570
3,010
2,480
2,590
1,630
1,900
1,980
1,050
674
1,760
1,920
2,100
1,950
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
14.9
15.4
19.2
12.0
17.1
16.0
15.0
15.5
16.4
15.6
14.6
13.0
11.0
11.8
10.1
10.2
8.5
9.2
15.9
8.0
9.6
9.1
7.6
8.5
8.2
6.1
5.0
8.1
8.1
8.1
8.4
63.1
61.7
59.3
58.6
60.0
63.5
63.1
64.5
64.9
65.0
65.0
65.0
65.5
65.0
65.0
65.0
65.0
65.0
64.4
65.0
64.0
61.9
65.9
69.8
75.9
74.8
75.0
64.1
64.2
64.8
68.2
182 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United Stetes
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09484590
09484600
09485000
09485100
09485500
09485900
09485950
09486000
09486300
09486800
09487000
09487100
09487140
09487250
09487400
09488500
09488600
09514200
09517000
09517200
09517280
09517400
09519600
09519750
09519760
09519780
09520100
09520110
09520130
09520160
09520170
Relation characteristic L H D 0 U
.
0
0
-
0
1
1
1
0
0
0
0
-
0
1
1
0
1
1
0
1
1
1
-
1
-
0
1
1
0
0
.1
0
-
0
1
0
0
0
0
0
0
-
1
0
0
0
0
0
0
0
0
0
-
0
-
0
0
0
1
0
.1
0
-
0
0
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
-
1
-
0
0
0
0
0
.0
0
-
0
1
0
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
-
0
-
0
0
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
Peak discharge (cubic indicated recurrence
2
....
9763,1203,030
956951
411,7102,010
73128116133
5,0904,9602,6202,4704,2803,7903,6403,510
777692
761,1301,920
167179805
1,620265336
1,4301,6403,1103,300
131154
1,0101,070
854877482413
1,130583806
----
501125196136120551485239226
3,0002,710
5
....
2,3007.8007,4102,7602,670
924,6105,070
177321270318
9,5209,3306,1305,6907,9107,2206,3906,5301,4501,360
1793,0904,660
369411
3,1604,640
660837
2.7303,3208.3908,430
312373
2,1202,3301,5401,720
747680
2,6301,8702,280
1,210468609191187922865463464
4,8504,720
10
_.__
3,62012,40011,4004,8304,490
1377,6008,420
272610418530
13,20012,9009,4308,46011,00010,0008,7709,5002,0101,930----
2724,9308.210
547655
6,2709,0501,0701,4503,8705,36014,40013,900
480624
3,0703,6502,1202,660
947881
4,1303,3104,100
1,910945
1,190226243
1,2101,180
661692
6,2706,540
feet per interval
25
5,78020,30018,0008,8607,830
20912,80013,800
4231,080
665880
18,60018,30014,70012,90015,60014,60012,50014,4002,8702,910----
4267,79013,600
8191,050
12,80016,5001,8202,4805,6608,640
25,80023,500
7471,0304,4805,7603,0004,2001,2301,240
6,5905,9107,090
3,0702.0202,250
267341
1,6301,720
9741,0808,3009,610
second) for (years)
50
..._
7,72027,60024,00013,10011,300
26517,70018,600
5551,460
8951,190
23,20023,00019,60017,10019,60018,70016,00018,6003,6103,800
55210,20017,8001,0501,390
20,00023,2002,5703,4207,28011,40037,90032,900
9861,3805,6807,5703,7705,5401,4501,550
8.7908,4509,770_____
4,1203,3103,340
297420
1,9802,2101,2601.4209,960
12,300
100
____
10,20036,40031,50018,80015,900
33623,70024,300
7031,9401,1701,570
28,30028,30025.20022,10024,10023,50020,00023,6004,4504,890
71912,90022,6001,3201,820
29,60031,7003,5004,5909,14014,60053,90045.1001,2601,8207.0009,7204,6407,1501,7001,950
11,60011.50013,000
5,4905,1804,850
325517
2,3702,8101,5801.840
11,80015,400
Maximum peak discharge
of record (cubic feet per second)
6,860
38,000
9,660
49
20,000
460
705
29,700
17.000
22,000
19,100
13,800
520
32,000
715
53,100
1,400
6,300
39,000
720
4.550
3.640
1.430
2,670
3,150
4.430
1,530
240
1,670
1,800
8,030
Basin, Climatic, and Flood Characteristics 183
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Stationnumber
09520200
09520230
09520300
09520350
09520400
09535100
09535300
09536100
09536350
09537200
09537500
09430500
09430900
09438200
09442630
09442660
09442680
09442690
09442692
09442695
09442700
09442740
09443000
09444000
09444200
09444400
09445500
09446000
09446500
09447000
09451800
FloodStation name region
Black Gap Wash near Ajo, Ariz.
Crater Range Wash near Ajo, Ariz.
Alamo Wash Tributary near Ajo,Ariz.
Mohawk Pass Wash at Mohawk, Ariz.
Ligurta Wash at Ligurta, Ariz.
San Simon Wash near Pisinimo,Ariz.
Vamori Wash at Kom Vo, Ariz.
Pitchfork Canyon Tributary nearFt Grant, Ariz.
Surprise Canyon near Dos Cabezas,Ariz.Leslie Creek near McNeal, Ariz.
Whitewater Draw near Douglas,Ariz.Gila River near Gila, N. Mex.
Duck Creek at Cliff, N. Mex.
Animas Creek near Cloverdale,N. Mex.
Mail Hollow near Luna, N. Mex.
Trout Creek at Luna, N. Mex.
San Francisco River near Reserve,N. Mex.Tularosa River near Aragon,N. Mex.
Tularosa River above Aragon,N. Mex.
Negro Canyon at Aragon, N. Mex.
Apache Creek near Apache Creek,N. Mex.Tularosa River near Reserve,N. Mex.San Francisco River near Alma,N. Mex.
San Francisco River near Glenwood,N. Mex.
Blue River near Clifton, Ariz.
Chase Creek near Clifton, Ariz.
Willow Creek near Point Of Pinesnear Morenci, Ariz.
Willow Creek near Double Circle Ranchnear Morenci, Ariz.Eagle Creek near Double Circle Ranchnear Morenci, Ariz.Eagle Creek above pumping plantnear Morenci, Ariz.Tollgate Wash Tributary nearClifton, Ariz.
13
13
13
13
13
13
13
13
13
13
13
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
14
Lati
tude, in decimaldegrees
32.
32.
32.
32.
32.
32.
31.
32.
32.
31.
31.
33.
32.
31.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
33.
32.
706
562
.100
.729
.676
.045
.948
.589
.011
.590
,352
,061
.967
,571
,794
,850
,737
.904
,891
,883
,931
,733
,368
247
291
172
379
354
300
070
850
Longi
tude, in decimaldegrees
112.
112.
112.
113.
114.
112.
112.
109.
109.
109.
109.
108.
108.
108.
108.
108.
108.
108.
108.
108.
108.
108.
108.
108.
109.
109.
109.
109.
109.
109.
109.
,845
,877
,771
,742
,294
,370
,343
,911
.353
.508
,584
,537
,600
,875
,950
,967
,771
.504
.515
,550
,662
,703
,910
,880
196
369
,650
,525
492
451
337
System
atic Drainage years area, in of square
record miles
18
17
22
15
15
15
15
14
14
13
62
59
29
28
16
32
28
12
20
27
17
28
23
20
20
14
23
24
24
43
14
12,
1,
0,
0,
1,
569,
1,250,
0,
0
79
1,023
1,864
228
157,
4,
31,
350,
89
94.
9,
94,
426,
1546,
1653.
506.
1.
102.
149.
377.
613.
0.
.10
.49
.90
.09
.99
.00
.00
.81
.65
.10
.00
.00
.00
.00
.20
.90
.00
.00
.00
.62
.60
.00
.00
,00
,00
,37
.00
.00
,00
,00
,12
Mean basin eleva
tion, in
feet
1,280
1,280
2,040
601
395
2,250
2,699
5,210
6,280
5,360
4,740
8,100
6,560
6,200
7,084
8,950
8,540
7,800
7,720
7,900
7,740
8,200
8,120
7,780
6,910
6,840
6,340
6,310
6,410
6,060
4,800
Mean Mean annual annual precipi- evapor- tation, ation,
in ininches
6.7
6.6
9.7
4.9
4.0
10.0
12.5
15.0
18.0
18.0
14.8
18.0
16.8
15.3
--
19.5
17.0
14.3
13.0
12.0
14.5
14.4
17.6
17.6
20.7
20.0
19.8
19.2
20.0
19.2
13.5
inches
75.4
70.4
64.4
75.0
75.2
65.0
65.0
65.0
69.0
69.2
70.7
44.9
51.5
74.1
40.7
40.0
44.2
44.8
44.8
44.8
44.6
44.9
45.1
45.1
46.2
48.4
44.2
44.0
44.8
48.7
55.0
184 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09520200
09520230
09520300
09520350
09520400
09535100
09535300
09536100
09536350
09537200
09537500
09430500
09430900
09438200
09442630
09442660
09442680
09442690
09442692
09442695
09442700
09442740
09443000
09444000
09444200
09444400
09445500
09446000
09446500
09447000
09451800
Relation characteristic L H D 0 U
1
0
1
0
1
1
0
1
0
1
0
0
0
1
1
0
0
-
1
1
0
0
1
0
1
-
1
1
1
0
-
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
-
0
1
0
0
0
1
0
-
0
0
0
0
-
0
1
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
-
0
0
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
1
0
0
0
1
0
0
0
1
0
0
-
1
0
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
1
Peak discharge (cubic feet per indicated recurrence interval
2
3924141031161511442022
185185
1,2501,670
7781,610
142132
Itlt59
438668
1,7101,8601,8801,9203,6603,530
7397575459
151156871885 -
56583
122211207290317341397
5,1104,9603,9303,8704,1703,990
58671680
1,4101,3802,4902,4402,7402,730
5
6728013293412682705254
551520
3,0203,9301,7103,590
246250112147
1,3501,8202,7703,2105,3205,4405,5105,2201,2901,420
106147489522
2,2702,350-
1,540203413532526962
1,070789
1,08013,00012,2008,6908,46010,5009,550
1901,3601,4302,9002,8305,6805,4307,3707,190
10
8681,240
5865853623848585
971853
5,0106,8802,7006,790
326359176252
2,4803,3603,5104,7309,4809,6706,7006,3801,7702,070
151281939
1,0503,9304,160
2,900321847907926
1,7702,0401,2601,970
22,00020,00013,50013,10017,50015,300
4181,9802,1804,2304,1408,8108,27012,20011,700
25
1,1201,9601,060
999500572142134
1,7701,4408,85011,8004,52011,700
437538275415
4,8105,9804,4707,06018,00018,1008,1707,9502,5003,260
219515
1,9402,1207,3407,640
4,620524
1,7001,6701,6703,3703,8002,1103,720
39,40033,80022,10020,90030,60024,900
6722,9603,4606,3406,220
14,20012,90020,50019,100
second) for tvears)
50
1,3002,5601,5301,390
615731197176
2,6102,03013,00016,1006,420
15,700526688362550
7,4308,4605,1908,820
27,60027,3009,2209,3103,1504,410278742
3,1403,31011,20011,300
6,200716
2,5502,5202,4405,0705,5402,9905,500
58,10047,80030,80028,60044,40034,500
9013,8404,6608,2508,14019,40017,30028,50026,000
100
1,4803,2902,1001,870
741923263228
3,6802,79018,70021,7008,920
20,400621873457714
11,10011,7005,91010,70040,90039,60010,20010,8003,9105,790
3441,0104,9104,94016,70016,300
8,070947
3,5803,7203,4707,2807,6904,1107,700
83,40066,00041,80038,00062,40046,500
1,1704,8606,08010,50010,40025,70022,50038,30034,500
Maximum peak discharge
of record (cubic feet per second)
940
590
510
117
1,590
12,500
10,400
375
191
4,600
5,060
35,200
6,900
3,400
264
2,790
9,830
181
660
5,200
2,900
3,020
56,600
37,100
30,000
600
3,710
7,500
30,000
36,400
6322 68 135 218 292 378
Basin, Climatic, and Flood Characteristics 185
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
09451900
09455800
09456000
09456400
09456680
09456820
09460150
09462200
09467120
08265000
08267000
08268500
08269000
08275000
08275500
08275600
08279000
08283500
08284100
08284300
08284500
08286650
08288000
08289000
08291000
08292000
08293700
08294300
08295000
07199000
07201000
Station name
Agricultural Research ServiceWatershed W-I near Safford, Ariz.Steins Creek at Steins, N. Mex.
San Simon River near San Simon,Ariz.Gold Gulch near Bowie, Ariz.
Agricultural Research ServiceWatershed W-V near Safford, Ariz.
Agricultural Research ServiceWatershed W-V near Safford, Ariz.Frye Creek near Thatcher, Ariz.
Agricultural Reserch ServiceWatershed W-II near Safford, Ariz.Salt Creek near Peridot, Ariz.
Red River near Questa, N. Mex.
Red River at mouth, near Questa,N. Mex.
Arroyo Hondo at Arroyo Hondo,N. Mex.
Rio Pueblo de Taos near Taos,N. Mex.
Rio Fernando de Taos near Taos,N. Mex.
Rio Grande del Rancho nearTalpa, N. Mex.
Rio Chiquito near Talpa, N. Mex.
Embudo Creek at Dixon, N. Mex.
Rio Chama at Park View, N. Mex.
Rio Chama near La Puente, N. Mex.
Horse Lake Creek above HeronReservoir near Park View, N. Mex.
Willow Creek near Park View,N. Mex.
Canjilon Creek above AbiquiuReservoir, N. Mex.
El Rito near El Rito, N. Mex.
Rio Ojo Caliente at La Madera,N. Mex.Santa Cruz River at Cundiyo,N. Mex.Santa Clara Creek near Espanola,N. Mex.
Arroyo Seco Tributary nearPojoaque, N. Mex.
Rio Nambe at Nambe Falls nearNambe, N. Mex.
Rio Nambe near Nambe, N. Mex.
Canadian Rivernear Hebron, N. Mex.
Raton Creek at Raton, N. Mex.
Flood region
14
14
14
14
14
14
14
14
14
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
16
16
Lati
tude , in decimal degrees
32
32
32
32
32
32
32
32
33
36
36
36
36
36
36
36
36
36
36
36.
36.
36,
36.
36.
35.
35.
35.
35.
35.
36.
36.
.841
.230
.225
.348
.422
.625
.744
.836
.271
.703
.648
.532
.439
.375
.298
.332
.211
.737
.662
.707
.668
.315
392
350
965
978
942
846
860
787
927
Longi
tude , in decimal degrees
109.521
109.000
109.175
109.603
109.657
109.600
109.837
109.994
110.304
105.568
105.693
105.685
105.503
105.549
105.582
105.578
105.913
106.578
106.632
106.745
106.704
106.485
106.239
106.044
105.904
106.172
106.020
105.908
105.935
104.462
104.439
System
atic Drainage years area, in of square
record miles
31
54
11
14
30
29
11
31
12
57
28
51
52
19
33
24
44
33
31
24
34
17
33
55
56
27
15
13
33
40
30
0
1
814
15
1
1
3
1
30
113
190
65
66
71
83
37
305
405
480
45
193.
144,
50,
419,
86.
34.
0.
25.
38.
229.
14.
.81
.26
.00
.00
.13
.19
.91
.07
.30
.00
.00
.60
.60
.70
.00
.00
.00
.00
.00
.00
.00
.00
.50
.00
,00
,50
,72
,10
,20
00
40
Mean basin eleva
tion, in
feet
3,350
4,431
4,830
5,170
4,550
3,650
8,400
3,800
3,490
9,930
9,500
9,730
9,500
8,870
9,400
9,350
8,980
9,270
9,000
7,970
8,000
6,300
8,700
8,640
9,190
7,230
5,845
9,380
9,100
8,300
8,100
Mean annual precipi tation,
in inches
8.0
14.9
10.9
10.0
9.0
25.0
12.0
16.0
21.0
22.0
20.0
25.0
20.0
22.0
22.0
21.0
22.0
24.0
18.0
18.0
--
22.0
16.0
20.0
20.4
--
27.0
22.0
18.0
17.8
Mean annual evapor
ation, in
inches
54.6
70.0
68.5
65.0
65.0
65.4
64.7
64.2
55.3
46.8
50.0
51.1
46.6
49.0
49.8
50.1
55.4
39.7
40.2
40.2
40.5
47.0
45.9
50.0
55.3
51.6
55.5
55.1
55.3
50.7
48.5
186 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
09451900
09455800
09456000
09456400
09456680
09456820
09460150
09462200
09467120
08265000
08267000
08268500
08269000
08275000
08275500
08275600
08279000
08283500
08284100
08284300
08284500
08286650
08288000
08289000
08291000
08292000
08293700
08294300
08295000
07199000
07201000
Relation characteristic L H D 0 U
0
-
1
0
1
0
-
1
0
0
0
0
1
-
1
0
1
0
0
-
1
1
1
0
1
1
1
0
0
1
0
0
-
1
0
0
0
-
0
0
0
0
0
0
-
0
0
1
0
0
-
1
0
0
0
0
0
0
1
1
1
0
1
-
1
0
0
0
-
1
0
0
0
0
1
-
1
1
0
0
0
-
1
0
0
1
0
0
0
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
-
0
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
7375
962,8903,020
51849984846871
82247240794801253253311312154154174174
2521531537171
1,0801,0804,0104,0004,0404,030
3891,1901,190
866872225225
1,0401,0402972979495
1021019595
200200
3,0903,070
420418
5
182188
2464,5205,0901,1801,110
210212148162
285650609
1,9101,830
442442472479319320363363
470269272155158
1,6101,6105,7705,7007,0506,960
7291,8301,8301,4101,460
406408
1,7101,710
624623229239216211227227635629
6,9006,5801,0401,010
10
287293
4025,6206,3901,8101,670
335342222247
6801,010
9222,9402,600
587590585608470472533534
703357369232242
2,0302,0306,9806,8209,3409,100
1,0702,3502,3501,8301,930
568576
2,1602,170
927925373398325312373374
1,1701,150
10,8009,3501,6701,530
25
464477
6467,0009,4202,8602,560
549562344404
1,0901,5601,3704,5603,870
791799731789717722802803
1,030478508355378
2,6402,6308,5608,26012,50012,000
1,5703,1403,1502,4302,640
831850
2,7402,7601,4201,410
642693505476653646
2,2602,18017,90017,2002,7702,700
second) for (years)
50
629647
8678,02012,3003,8403,380
751769456553
1,4602,0201,7305,9704,990
956971843936946953
1,0401,040
1,300574624466503
3,1503,1409,7609,35015,10014,300
1,9703,8403,8502,9203,2401,0801,1103,1703,2101,8801,860
921994677632953925
3,4603,280
25,10023,5003,8303,670
100
824848
1,1209,02015,8005,0104,360
9921,010
587728
1,9002,5102,1207,5606,2801,1301,150
9571,0901,2201,2301,3201,320
1,640676752593651
3,7103,690
11,00010,40017,80016,700
2,5704,6204,6303,4703,9601,3701,4103,6003,6502,4302,4001,2801,390
883843
1,3601,3005,0904,770
34,20032,7005,1405,060
Maximum peak discharge
of record (cubic feet per second)
434
317
5,350
2,550
671
508
96
997
3,200
886
730
1,060
1,050
219
497
309
4,200
10,000
11,200
3,960
4,500
2,450
1,240
3,140
2,420
970
508
1,090
5,580
62,400
3,990
Basin, Climatic, and Flood Characteristics 187
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
07201200
07201450
07203000
07203600
07207500
07208500
07211000
07215500
07216500
07218000
07220000
07220900
07221000
08080510
08080540
08080600
08080700
08081200
08081500
08082100
08082180
08120500
08123650
08313100
08313400
08316600
08316650
08316700
08317100
08317500
08317600
Station name
Chicorico Creek Tributarynear Raton, N. Mex.Green Mountain Arroyonear Raton, N. Mex.
Vermejo River nearDawson, N. Mex.
Rio del Piano Tributarynear Taylor Springs, N. Mex.Ponil Creek near Cimarron, N. Mex.
Rayado Creek at Sauble Ranchnear Cimarron, N. Mex.Cimmaron River atSpringer, N. Mex.
Mora River at La Cueva, N. Mex.
Mora River near Golondrinas,N. Mex.
Coyote Creek near Golondrinas,N. Mex.
Sapello River at Sapello, N. Mex.
Dog Creek near Shoemaker, N. Mex.
Mora River near Shoemaker, N. Mex.
Guest-Flowers Draw nearAspermont, Tex. (Disc.)
McDonald Creek near Post, Tex.(Disc.)
Running Water Drawnear Clovis, N. Mex.Running Water Drawat Plainview, Tex. (Disc.)
Croton Creek near Jayton, Tex.
Salt Croton Creeknear Aspermont, Tex.
Stinking Creek nearAspermont, Tex. (Disc.)
North Croton Creek nearKnox City, Tex.Deep Creek near Dunn, Tex.
Beals Creek aboveBig Springs, Tex. (Disc.)Canada Ancha Tributary nearSanta Fe, N. Mex.
Bland Canyon near Cochiti, N. Mex.
near Frijoles Arroyo nearSanta Fe, N. Mex.
Arroyo de los Frijoles nearSanta Fe, N. Mex.
Arroyo de los Frijoles nearSanta Fe, N. Mex.
Arroyo Yupa Tributary nearCerrillos, N. Mex.
Galisteo Creek at Canoncito,N. Mex.San Cristobal Arroyo nearGalisteo, N. Mex.
Flood region
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Lati
tude, in decimal degrees
36.
36.
36.
36.
36.
,36.
36.
35.
35.
35.
35.
35.
35.
33.
33.
34.
34.
33.
33.
33.
33.
32.
32.
35,
35.
35.
35.
35.
35.
35.
35.
828
783
681
450
574
372
360
941
891
917
,770
,826
800
,124
,351
532
,179
288
401
233
,383
,574
,250
,735
,703
719
,704
,701
533
551
,382
Longi
tude, in decimal degrees
104.333
104.262
104.786
104.376
104.946
104.969
104.598
105.250
105.163
105.164
105.251
104.891
104.783
100.137
101.227
103.201
101.702
100.431
100.408
100.213
100.081
100.907
101.491
106.117
106.416
105.958
105.972
106.008
106.146
105.822
105.851
System
atic Drainage years area, in of square
record miles
16
12
58
13
42
64
57
55
61
58
17
31
69
10
13
32
39
27
21
18
21
34
21
31
23
13
14
14
20
29
32
5.
18.
301.
6.
171.
65.
1,032.
173,
267.
215.
132.
18.
1,033.
3.
79.
95.
382.
290.
64.
88.
251.
188.
1,505,
1.
7
0.
1.
2.
0.
11.
116
18
20
00
,71
,00
00
,00
,00
,00
,00
.00
.40
,00
.02
.20
.00
.00
.00
.30
,80
.00
.00
,00
.23
.57
.33
.30
.92
.47
,30
.00
Mean basin eleva
tion, in
feet
6,480
6,499
9,350
6,148
9,350
10,400
9,160
9,540
9,400
8,760
7,950
7,200
9,020
4,520
--
1,897
2,449
6,600
8,900
7,150
7,100
6,900
6,017
8,000
7,110
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
_-
--
19.0
18.0
21.0
17.9
21.0
20.5
19.0
23.0
17.0
19.0
23.0
15.8
19.5
21.0
21.5
--
23.5
19.0
11.0
17.0
13.0
13.0
12.0
10.5
17.1
13.7
50.2
50.9
51.3
55.1
47.3
50.5
55.3
48.2
51.2
51.0
50.4
53.0
53.8
66.6
69.9
69.5
71.0
67.4
67.3
66.8
66.3
69.7
71.6
55.6
50.2
55.6
55.7
55.5
55.2
49.5
50.1
188 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
07201200
07201450
07203000
07203600
07207500
07208500
07211000
07215500
07216500
07218000
07220000
07220900
07221000
08080510
08080540
08080600
08080700
08081200
08081500
08082100
08082180
08120500
08123650
08313100
08313400
08316600
08316650
08316700
08317100
08317500
08317600
Relation characteristic L H D 0 U
-
0
0
0
1
1
1
0
1
1
1
0
-
0
-
-
0
0
0
0
1
-
-
1
1
1
0
-
0
1
-
0
0
0
0
0
0
1
0
0
0
0
-
1
-
-
0
0
0
0
1
-
-
0
0
0
0
-
0
0
-
0
0
1
0
0
1
0
1
1
0
0
-
0
-
-
0
0
0
0
0
-
-
0
0
0
0
-
0
0
-
0
0
0
0
0
0
0
0
0
0
0
-
0
-
-
0
0
0
0
0
-
-
0
0
0
0
-
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
1
0
1
1
0
0
0
0
0
1
1
0
0
0
0
1
0
0
Peak discharge (cubic indicated recurrence
2
160
3091,6601,660
106109452456155158785799574576771774594598
2,4602,4201,0201,0102,2202,220____
173970970
1,050-
2,1802,7302,7202,7502,710
589598
1,2701,2802,3302,320--._
4,420-
893740
140137508496417409
54885876
1,6001,590
5
508
9473,2503,280
295379
1,1901,290
350427
2,0902,430
890996
1,6201,7301,2701,3804,2003,8802,3402,2005,4005,490----
5862,6302,710
3,230 -
6,4506,0305,9407,4706,7301,3001,5904,2104,3104,7104,690
12,600--
30075
150243224
1,020869
1,6501,400
1861,3101,2403,2703,160
10
788
1,4604,6004,770
487761
2,0002,380
572908
3,6104,9801,1201,6202,4502,9201,9202,4105,5604,7403,6103,0208,3908,750
9394,6104,620
5,020 -
9,8908,7608,57012,8009,5001,9903,0708,1307,8807,2207,140- _
19,100____
477108403322290
1,4701,0103,3302,090____
2991,6001,4504,6704,300
feet per interval
25
1,320
2,4806,6406,800
8131,0103,5403,7301,0101,1806,6507,3701,4401,7203,9104,1703,0203,2907,5107,3205,7505,46013,20013,500
____
1,6408,6608,610____
9,110
18,30012,70012,90023,10021,0003,1503,93016,80016,40011,90012,000
35,700
803160334433432
2,1401,9006,9805,910
4981,9701,9606,7506,670
second) for (years)
50
1,880
3,4808,4108,8201,1201,5505,1505,5201,5101,880
10,00011,5001,6802,3205,3405,9204,0804,6809,1209,0007,7607,180
17,50018,100
2,44013,20012,900
13,100 -
26,00015,80016,70034,10029,3004,2506,030
27,30025,70016,80017,000
50,200
1,180206591523556
2,7302,31011,2008,580
7382,2502,3108,5108,440
100
2,910
5,57010,40011,3001,4702,0807,2508,0002,2102,75014,60017,0001,9502,9907,1308,1305,3706,38010,90011,70010,2009,660
22,40023,800
3,19019,70019,000
____
18,700 -
38,20019,10020,90048,70042,7005,5807,95042,50040,10023,40023,700
76,500
1,650259795619681
3,4002,98017,10013,500
1,0102,5302,75010,40010,800
Maximum peak discharge
of record (cubic feet per second)
1,340
5,030
12,600
724
5,630
9,000
29,500
1,530
14,000
4,050
6,420
7,180
15,200
410
15,300
8,000
12000
10,600
29,900
3,260
32,100
36,400
255
298
174
360
1,900
5,340
568
2,000
9,500
Basin, Climatic, and Flood Characteristics 189
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
08317700
08317720
08317800
08318000
08318900
08321500
08323000
08324000
08329000
08330500
08330600
08331650
08331700
08334000
08340500
08341300
08343100
08348500
08353500
08354000
08358600
08359400
08360000
08361650
08361700
08361800
08363100
08363200
08365600
08374000
08374500
Station name
Tarhole Canyon near Galisteo,N. Mex.
Canada de la Cueva near Galisteo,N. Mex.
Canada de las Minas Tributarynear Santa Fe, N. Mex.Galisteo Creek at Domingo,N. Mex.
San Fedro Creek near Golden,N. Mex.
Jemez River below East Forknear Jemez Springs, N. Mex.
Rio Guadalupe at Box Canyonnear Jemez, N. Mex.Jemez River near Jemez, N. Mex.
Jemez River below Jemez CanyonDam, N. Mex.
Tijeras Arroyo at Albuquerque,N. Mex.
Tijeras Arroyo near Albuquerque,N. Mex.
Canada Montoso near Scholle,N. Mex.
Abo Arroyo Tributary near Scholle,N. Mex.
Rio Puerco above Arroyo Chico nearGuadalupe, N. Mex.
Arroyo Chico near Guadalupe,N. Mex.
Bluewater Creek above Bluewater Damnear Bluewater, N. Mex.Grants Canyon at Grants, N. Mex.
Encinal Creek near Casa Blanca,N. Mex.
La Jencia Creek near Magdalena,N. Mex.
Rio Salado near San Acacia,N. Mex.
Chupadera Wash Tributary atBingham, N. Mex.
Lumber Canyon Tributary nearMonticello, N. Mex.
Alamosa Creek near Monticello,N. Mex.
Fercha Creek near Kingston,N. Mex.Percha Creek near Hillsboro,N. Mex.
Fercha Creek at Caballo Dam,near Arrey, N. Mex.
Rio Grande Tributary nearRadium Springs, N. Mex.
Aleman Draw at Aleman, N. Mex.
McKelligon Canyon at El Paso,Tex. (Disc.)
Alamito Creek near Presidio, Tex.
Terlingua Creek near Terlingua,
Flood region
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Lati
tude , in decimal degrees
35
35
35
35
35
35
35
35
35
35
35
34
34
35
35
35
35
35
34
34
33
33
33
32
32
32
32
33
31
29
29
.365
.437
.607
.512
.229
.827
.731
.662
.390
.061
.001
.400
.403
.636
.592
.267
.161
.143
.162
.297
.900
.400
.569
.918
.915
.900
.501
.000
.822
.521
.200
Longi
tude, in decimal degrees
105.844
106.012
105.912
106.317
106.300
106.647
106.762
106.743
106.534
106.478
106.655
106.483
106.510
107.166
107.189
108.114
107.837
107.465
107.210
106.900
106.333
107.267
107.592
107.649
107.601
107.317
106.951
107.006
106.469
104.294
103.604
System
atic Drainage years area, in of square
record miles
34
16
29
26
33
24
37
42
13
34
32
25
32
35
43
24
25
26
30
37
26
24
40
34
27
24
31
25
20
52
52
2
1
0
640
45
173
235
470
1,038
75
133
35
0
420
1,390
75
13
6
195
1,380
1
0
403
21
35
119
0
25
2
1,504
1,070
.15
.79
.56
.00
.20
.00
.00
.00
.00
.30
.00
.00
.23
.00
.00
.00
.00
.19
.00
.00
.29
.90
.00
.50
.40
.00
.40
.50
.30
.00
.00
Mean basin eleva
tion, in
feet
6.700
6,120
7,195
6,000
6,860
9,070
8,250
8,400
7,000
7,020
6,800
6,260
6,080
7,550
6,900
8,200
7,000
7,784
7,180
6,500
5,440
5,130
7,530
7,070
6,800
6,100
4,450
5,000
--
4,626
3,936
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
13.0
15.0
13.0
12.3
25.0
22.0
23.0
17.0
15.5
14.8
12.5
13.0
16.0
14.0
16.3
11.0
11.9
12.5
12.0
--
9.0
16.0
18.4
17.5
14.6
10.0
10.0
_-
9.5
10.0
50.0
52.6
53.8
55.6
49.2
42.9
48.9
49.9
55.4
56.6
60.3
52.4
53.5
50.0
50.1
49.3
49.3
50.2
50.5
60.0
54.8
59.8
47.7
53.3
56.2
73.7
72.8
69.2
73.0
71.4
71.1Tex.
190 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
08317700
08317720
08317800
08318000
08318900
08321500
08323000
08324000
08329000
08330500
08330600
08331650
08331700
08334000
08340500
08341300
08343100
08348500
08353500
08354000
08358600
08359400
08360000
08361650
08361700
08361800
08363100
08363200
08365600
08374000
08374500
Relation characteristic L H D 0 U
0
0
-
0
1
1
1
0
1
1
1
1
0
1
1-
1
0
-
0
-
0
1
1
0
0
0
1
-
0
1
0
0
-
0
1
0
0
0
0
0
0
0
0
0
0
-
0
1
-
0
-
0
0
1
1
0
0
0
-
1
0
0
0
-
0
0
0
1
0
0
0
0
1
0
0
1
-
0
1
-
1
-
0
0
0
0
0
0
0
-
0
0
0
0
-
0
0
0
0
0
0
0
0
0
0
0
0
-
0
0
-
0
-
0
0
0
0
0
0
0
-
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
0
0
0
0
0
1
0
0
Peak discharge (cubic feet per indicated recurrence interval
2
330327104104
576,3806,310
926920589591425432
1,4401,4404,2204,180
8308297857893843858585
2,1202,1104,0304,020
607253253119120
1,0206,8206,780
89174172
2,0802,070
530528
1,0201,0101,1601,160
124123
1,6301,610
1657,5307,510
13,40013,300
5
745704267279
19511,20010,5001,7901,750
9561,100
8401,0402,6102,7508,5808,3502,1302,1401,2701,4701,1701,200
144142
3,1903,2806,8206,870
1,770549577374397
2,92015,70015,100
300339332
4,4204,360
942959
2,2302,1403,2603,340
204209
4,1503,830
57212,80012,80020,40019,700
10
1,130964447479
31215,00013,0002,6302,4801,2301,8101,2102,0503,5604,23012,40011,8003,4903,4601,6502,5602,1302,120
192195
3,9504,5409,0809,480
2,670844954717763
4,37023,00020,800
476479472
6,4506,2301,3101,4203,4903,1305,6105,740
262304
6,7705,400
92517,20017,50025,10023,300
25
1,7701,690
787801
51920,50020,0004,0904,0501,5901,9801,7802,2604,9305,38018,20018,6005,9105,9102,2002,7904,0403,990
266272
4,9405,43012,40012,900
4,5801,3601,4301,4901,480
7,61033,30032,800
799691701
9,5509,5501,9202,0105,8005,62010,00010,100
338372
11,40010,700
1,63023,90024,60031,10031,000
second) for (years)
50
2,3402,1901,1401,170
76425,00024,5005,5505,4701,8802,6802,3003,3506,0707,120
23,30024,6008,3108,3302,6604,0506,1405,950
331355
5,7106,90015,30016,500
6,2901,8802,0402,4502,380
10,40041,40040,800
1,170876928
12,20012,3002,4802,7108,1907,800
14,60014,800
396496
1600014,400
2,45029,80031,70035,60036,200
100
3,0202,8801,6101,660
1,07029,90031,100
' 7,4007,5102,1903,7002,8904,6207,3209,280
29,10033,90011,30011,5003,1705,1408,9808,850
406440
6,5008,74018,50021,300
10,7002,5302,8303,8803,780
18,00049,80051,000
1,6601,0801,16015,20016,0003,1603,56011,30011,00020,40020,700
455559
21,60019,800
3,04036,60039,80040,10042,000
Maximum peak discharge
of record (cubic feet per second)
2,440
919
652
22,800
10,800
1,700
3,190
5,900
23,100
6,500
2,530
4,700
301
6,940
15,200
3,570
1,550
4,330
4,830
36,200
620
778
10,800
3,740
12,200
15,400
332
16,400
3,060
56,400
34,900
Basin, Climatic, and Flood Charactaristics 191
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
08379300
08379500
08379550
08379600
08380300
08380500
08381000
08382000
08382500
08382900
08383200
08383210
08383300
08383370
08385530
08385600
08385670
08385690
08385700
08387000
08388000
08389000
08389060
08389500
08390050
08390100
08390150
08390500
08393200
08393600
08393900
Station name
Tecolote Creek at Tecolote,N. Hex.
Fecos River near Anton Chico,N. Hex.
Canon Blanco near Leyba, N. Mex.
Pecos River Tributary nearDilia, N. Mex.Sandoval Canyon at Gallinas,N. Mex.
Gallinas Creek near Montezuma,N. Mex.Gallinas Creek at Montezuma,N. Mex.
Gallinas River near Lourdes,N. Mex.
Gallinas River near Colonias,N. Mex.
Pecos River Tributary nearPintada, N. Mex.
Fintada Arroyo Tributary nearClines Corners, N. Mex.Pintada Arroyo Tributary nearEncino, N. Mex.
Fintada Arroyo near Santa Rosa,N. Mex.Pecos River Tributary nearPuerto de Luna, N. Mex.
Alamos a Creek Tributary nearJordan, N. Mex.
Yeso Creek near Fort Sumner,N. Mex.
Aragon Creek Tributary nearEncinoso, N. Mex.
Bonita Canyon Tributary nearCorona, N. Mex.
Cloud Canyon near Gallinas,N. Mex.
Rio Ruidoso at Hollywood,N. Mex.
Rio Ruidoso at Hondo, N. Mex.
Rio Bonito near Ft. Stanton,N. Mex.
Rio Bonito Tributary nearFt. Stanton, N. Mex.
Rio Bonito at Hondo, N. Mex.
Rio Hondo Tributary at Tinnie,N. Mex.
Rio Hondo at Picacho, N. Mex.
Gallo Canyon near Picacho, N. Mex.
Rio Hondo at Diamond A Ranchnear Roswell, N. Mex.Rocky Arroyo above Two RReservoir near Roswell, N. Mex.North Spring River at Roswell,N. Mex.
Eight Mile Draw near Roswell,N. Mex.
Flood region
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Lati
tude, in decimal degrees
35
35
35
35,
35
35.
35
35
35
34
34
34
34
34
34
34
33
34
34,
33,
33,
33,
33,
33,
33,
33.
33.
33.
33.
33.
33.
.456
.179
.221
.214
.689
.652
.654
.471
.182
.979
.844
.811
.889
.876
.800
.267
.683
.233
.133
.327
.383
.518
.521
.389
.371
.357
.290
.349
.285
,396
,417
Longi
tude, in decimal degrees
105.282
105.108
105.670
105.081
105.355
105.318
105.275
105.160
104.900
105.094
105.585
105.567
104.731
104.637
103.967
104.283
105.567
105.617
105.667
105.627
105.275
105.486
105.468
105.275
105.217
105.157
105.180
104.851
104.796
104.548
104.650
System
atic Drainage years area, in of square
record miles
31
66
12
33
26
70
57
12
35
23
24
23
27
26
23
35
24
24
30
33
40
31
29
38
14
14
24
47
18
28
35
122,
1,050
11
0
7
84
87
313
610
16
29
0
896
0
9,
242
6
0
1
120,
290
85,
0,
295,
0,
715,
1.
947.
31.
19.
397.
.00
.00
.20
.16
.60
.00
.00
.00
.00
.00
.20
.55
.00
.37
.71
.00
.07
.60
.85
.00
.00
.0
.72
.00
.23
.00
,32
.00
.00
50
,00
Mean basin eleva
tion, in
feet
7,390
7,920
6,659
5,450
7,600
7,810
7,800
7,500
5,920
--
7,065
6,459
6,210
4,600
4,950
4,720
6,780
6,735
--
9,060
7,760
8,650
7,900
5,150
7,740
7,400
4,550
3,600
3,740
Mean annual precipi tation,
in inches
19.6
18.0
--
14.0
22.6
22.0
21.5
19.0
17.0
--
16.0
--
13.5
13.0
15.5
13.0
19.0
15.4
16.0
25.0
21.0
21.0
16.0
19.0
__
20.0
18.0
13.4
12.0
14.3
Mean annual
evapor
ation, in
inches
52.5
56.3
49.7
56.4
48.6
50.1
50.7
53.2
59.8
58.0
50.7
50.7
63.0
63.6
69.4
75.0
54.4
51.3
51.9
50.3
54.6
52.5
52.5
54.6
55.7
58.0
57.8
65.6
66.9
72.7
70.4
192 Methods for Estimating Magnitude and Frequancy of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
08379300
08379500
08379550
08379600
08380300
08380500
08381000
08382000
08382500
08382900
08383200
08383210
08383300
08383370
08385530
08385600
08385670
08385690
08385700
08387000
08388000
08389000
08389060
08389500
08390050
08390100
08390150
08390500
08393200
08393600
08393900
Relation characteristic L H D 0 U
00000
10000
- - - - 1
- - - - 1
00000
10100
00000
00000
10000
- - - - 1
00000
- - - - 1
10000
11000
- - - - 1
10000
10000
- - - - 1
- - - - 1
10000
10000
00000
- - - - 1
00000
- - - - 1
- - - - 1
- - - - 1
00000
00000
10000
- - - - 1
Peak discharge (cubic indicated recurrence
2
1,3601,3506,4406,420
____
233
329132
618618480481
2,7802,7403,4103,400
3469095
521,9401,960
9797
3271,4301,440
478473
55
99255262944949600601
621,9901,980
38
2,400
963,0903,090
664662
1320
5
3,5003,390
11,50011,300
722
115371397
1,6101,6301,2001,2504,1204,0906,4506,460
1,090163301
1763,2703,900
225222
1,0803,5103,710
791768
187
327563741
2,4402,5801,5801,640
2125,0604,970
134
6,760
3289,6809,6402,4502,340
71251
10
5,8505,250
16,10015,400
1,110
187812836
2,6602,7001,9402,1405,0405,5209,0909,290
1,700224768
2804,1806,880
361351
1,7105,7006,4501,0401,020
297
514892
1,6004,2704,7002,5502,730
3378,0207,540
217
10,100
52418,20017,3004,7603,960
162893
feet per interval
25
10,3009,950
23,60023,500
1,870
3091,9501,9004,5704,5903,2303,3406,2407,150
13,20013,600
2,950314640
4605,3007,200
619612
3,0409,690
10,2001,4101,440
490
8581,5101,9108,1508,3404,0704,210
55912,80012,600
360
18,300
88736,80036,1009,5208,840
380805
second) for (years)
50
14,90014,00030,60030,500
2,630
4643,5003,2606,4906,5204,5004,7407,1409,440
16,90018,000
4,260391
1,110
6686,110
10,500892884
4,49013,80015,0001,7201,840
714
1,2402,1603,010
12,70013,0005,3805,720
81817,10016,800
537
25,400
1,31058,80056,40014,80013,100
6461,610
100
21,00020,30038,90039,600
4,200
6086,0105,6108,9109,0806,0606,5108,070
12,70021,20023,400
6,300477
1,520
9656,880
13,4001,2501,220
5,96018,90020,4002,0602,300
1,030
1,8303,0204,350
19,40019,9006,8107,560
1,17022,10022,400
716
42,100
1,80090,50087,40021,80019,5001,0302,120
Maximum peak discharge
of record (cubic feet per second)
20,000
73,000
1,440
184
2,530
7,120
11,600
6,680
26,700
6,600
305
145
4,300
1,450
2,850
14,800
1,610
112
706
2,120
42,700
4,100
512
28,200
420
115,000
2,400
54,800
12,000
387
22,2002,200 6,520 9,980 18,400 26,200 38,700
Basin, Climatic, and Flood Charactaristics 193
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES Continued
Station number
08394500
08397600
08398500
08400000
08401200
08401800
08401900
08405050
08405100
08405500
08408500
08411500
08424500
08431700
08431800
08435800
08444400
08447020
08478500
08480650
08480700
08481000
08481100
08481500
08482000
Station name
Rio Felix at Old Hwy. Bridge,near Hagerman, N. Mex.
Rio Penasco near Dunk en,N. Mex.
Rio Fenasco at Dayton, N. Mex.
Fourmile Draw near Lakewood,N. Mex.South Seven Rivers near Lakewood,N. Mex.
Rocky Arroyo near Carlsbad,N. Mex.
Rocky Arroyo at Hwy. Bridgenear Carlsbad, N. Mex.Last Change Canyon Tributarynear Carlsbad Caverns, N. Mex.Mosley Canyon near White City,N. Mex.
Black River above Malaga,N. Mex.
Delaware River near Red Bluff,N. Mex.Salt Screwbean Draw near Orla,Tex. (Disc.)
Madera Canyon near Toyahvale,Tex. (Disc.)
Limpia Creek above Ft. Davis, Tex.
Limpia Creek below Ft. Davis,Tex. (Disc.)
Coyanosa Draw near Ft. Stockton,Tex. (Disc.)
Three Mile Mesa Creek nearFt. Stockton, Tex. (Disc.)Independence Creek near Sheffield,Tex.
Mimbres River at Deming, N. Mex
Minnie Hall Draw near ThreeRivers, N. Mex.Indian Creek near Three Rivers,N. Mex.Three Rivers at Three Rivers ,N. Mex.Tularosa Basin Tributarynear Three Rivers, N. Mex.
Rio Tularosa near Bent, N. Mex.
Rio Tularosa near Tularosa,N. Mex.
Flood region
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
16
Lati
tude, in decimal degrees
33.125
32.882
32.743
32.672
32.589
32.467
32.506
32.292
32.250
32.229
32.023
31.878
30.868
30.613
30.681
31.041
30.838
30.452
32.283
33.417
33.369
33.303
33.300
33.145
33.093
Longi
tude, in decimal degrees
104.
105.
104.
104.
104.
104.
104.
104.
104.
104.
104.
103.
103.
104.
103.
103.
102.
101.
107.
106.
105.
106.
106.
105.
105.
344
178
414
369
421
467
374
606
333
151
054
947
969
001
792
137
841
733
760
083
890
072
083
897
976
System
atic Drainage years area, in of square
record miles
56
33
35
34
24
14
23
28
28
41
49
15
17
20
16
15
10
11
28
24
31
22
25
41
11
932.
583.
1,060.
265.
220.
254.
285.
0.
14.
343.
689.
464.
53.
52.
227.
1,180.
1.
763.
170.
9.
6.
96.
13.
120.
140.
00
00
00
00
00
00
00
20
60
00
00
00
80
40
00
00
04
00
00
70
80
00
80
00
00
Mean basin eleva
tion, in
feet
7,070
8,000
7,000
4,685
4,020
4,890
4,630
4,180
3,625
4,540
4,160
3,679
5,984
5,546
--
--
6,500
5,440
7,900
6,430
5,587
7,580
7,400
Mean Mean annual annual precipi- evapor- tation, ation,
in in inches inches
16.0
21.0
18.0
14.0
14.0
13.2
14.5
13.9
--
15.0
14.0
9.5
12.0
18.0
--
--
14.0
16.0
26.6
21.2
15.6
21.0
20.0
77.6
55.8
75.9
76.8
75.0
72.3
76.2
65.5
74.6
80.2
80.1
80.0
67.4
67.7
67.4
76.0
75.4
75.1
64.0
60.8
55.1
60.7
60.8
56.3
61.3
194 Methods for Estimating Magnitude and Frequency of Floods in the Southwestern United States
BASIN, CLIMATIC, AND FLOOD CHARACTERISTICS FOR STREAMFLOW-GAGING STATIONS IN THE SOUTHWESTERN UNITED STATES--Continued
Station number
08394500
08397600
08398500
08400000
08401200
08401800
08401900
08405050
08405100
08405500
08408500
08411500
08424500
08431700
08431800
08435800
08444400
08447020
08478500
08480650
08480700
08481000
08481100
08481500
08482000
Relation characteristic L H D 0 U
- - - - 1
10000
10000
11000
- - - - 1
- - - - 1
- - - - 1
10000
10000
01000
01000
- - - - 1
- - - - 1
- - - - 1
10000
- - - - 1
- - - - 1
11000
10100
10000
- - - - 1
00000
1 0 1 0 0
- - - - 1
- - - - 1
Peak discharge (cubic feet per indicated recurrence interval
2
....
3,7401,3301,3402,5202,540
800814
__
1,740
1,800____
2,010141140
1,8701,8502,5502,5503,7903,790
_.__
2,700_.__
760
7541,9301,920
4,140___.
1142,2602,300
666710902892
____
2092,1002,080
267268
_---
930
1,120
.
10,4,4,7,7,3,3,-
5,-
5,-
6,
3,3,9,9,
10,10,
-
8,-
2,-
2,3,3,-
12,-
8,8,1,2,1,1,-
5,4,
-
2,-
3,
5
...
900420560540910350610
270
420___
070288272610350510300600500
080
370
350010340
000 405770980220320850720
672000670948966___
750
330
10
....
16,7008,3208,420
13,50014,5007,1307,680
8,160____
8,360
9,380416366
5,2004,290
18,20016,50018,80018,000
....
12,500
3,690
3,6703,8205,340
18,200____
66218,90016,6001,6606,0502,7402,290
____
1,0507,7606,4701,7601,740_-__
4,180____
5,100
25
____
31,50016,40016,300
25,30025,900
16,10016,200
____
15,100____
15,400
17,400610
5927,8007,420
35,30034,200
35,40035,000
____
23,400____
6,640
6,6004,9706,350____
34,400____
1,16044,60040,7002,280
5,0404,2004,000
____
1,80012,30011,7003,2803,240
7,380.___
9,130
second) for (years)
50
____
44,70025,40024,80038,00039,10027,30026,900
-___
21,700
22,100
25,000779760
10,2009,530
53,20050,40054,10052,700
33,500
9,600
9,5505,9009,170
48,600
1,76079,90066,5002,7808,8805,5805,230
2,59016,40015,3004,8204,730
10,400
13,000
64373755564442
30
31
35
131276728078
46
13
136
11
71
2137114
312
76
32120
66
16
19
100
____
,700,800,600,000,400,000,800
,500
,700
,200967945
,100,400,300,700,000,100
,800____
,600
,500,910,600____
,500____
,110,000,000,310,000,240,910
,840,100,300,750,660
,600
,900
Maximum peak discharge
of record (cubic feet per second)
74
70
29
29
20
63
31
16
74
81
40
5
8
5
12
78
2
4
15
2
4
9
,000
,000
,800
,300
,100
,300
,600
683
,400
,600
,400
,600
,120
,610
,520
,600
350
,100
,370
,970
990
,000
,340
,280
,640
Basin, Climatic, and Flood Characteristics 195
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"Publications of the U.S. Geological Survey, 1971-1981" may be purchased by mail and over the counter in paperback book form (two volumes, publications listing and index) and as a set of microfiche.
Supplements for 1982, 1983, 1984, 1985. 1986. and for sub sequent years since the last permanent catalog may be purchased by mail and over the counter in paperback book form.
State catalogs, "List of U.S. Geological Survey Geologic and Water-Supply Reports and Maps For (State)," may be pur chased by mail and over the counter in paperback booklet form only.
"Price and Availability List of U.S. Geological Survey Publications," issued annually, is available free of charge in paperback booklet form only.
Selected copies of a monthly catalog "New Publications of the U.S. Geological Survey" are available free of charge by mail or may be obtained over the counter in paperback booklet form only. Those wishing a free subscription to the monthly catalog "New Publications of the U.S. Geological Survey" should write to the U.S. Geological Survey, 582 National Center, Reston. VA 20192.
Note Prices of Government publications listed in older cata logs, announcements, and publications may be incorrect. There fore, the prices charged may differ from the prices in catalogs, announcements, and publications.